While an attempt has been made to be as comprehensive as possible in the Science Fiction Index, a line had to be drawn somewhere and there are a number of titles you might expect to find here which have been deliberately excluded. These fall into four major categories:
The original index compiled by Stephen T. Miller and William G. Contento was created at a time when few other "genre" indexes had been written and, as such, indexed a number of "fringe titles", particularly in the "hero pulp" and "weird menace" fields, which has some elements of SF but do not really qualify as science fiction, fantasy or weird fiction. As these have now been fully indexed elsewhere, particularly in the Crime Fiction Index and the Adventure Fiction Index there seems no need to repeat them in this index. The titles concerned are:
The original index also contained a number of magazines which typically contained little or no SF, but which published special SF issues, or which had some related connection to the genre. In many cases other issues of the same magazine are already indexed in the Fictionmags Index so it seems sensible to exclude those magazines from this index as well. The titles concerned are:
The SFFWF field is an incredibly prolific one and there are (literally) an unknown number of minor magazines, ranging from the fanzines of the 1930s to the online magazines of the 2010s, many of which have not even been catalogued, let alone indexed. In some cases, partial listings of these titles are available in the Fictionmags Index while in others little is known beyond the magazine title and rough publication details. Over time, hopefully, some of these titles will be fully indexed and will be added to the Science Fiction Index, but, for now, the following titles have been excluded:
| Abortions | Dragonwings | Jinnia Clan Journal | Schlock! Webzine |
| Absent Willow Review | The Dream Cell | Jinx | Science*Fiction [1945] |
| Ad Astra [1965] | Dream Quest | Kasma SF Magazine | Science Fiction Scout |
| Adbhut | Dream Scene | Kenoma | Scienti-Comics |
| Afterburn SF | Duckspeak | Kinda Kinky | Scifaikuest |
| Agog | Ecce | Klein Bottle | SciFi Dimensions |
| Aleph-Null | Eclipse [1966] | Knights | SciFi Freedom |
| Alien Culture | Eclipse [1970] | The Kore | SciFi Paradox |
| Alien Landings | Edge of Twilight | Labyrinth Inhabitant | Sci-Fi Short Story Magazine |
| Alien Skin | eFantasy | Lakeside Circus | Scorched Earth |
| alphaDrive | Eldritch Science | Laser & Sword Magazine | Scream Queens Illustrated |
| Altair [1950] | Electric Wine | Lathered in Crimson | SDO Fantasy |
| Altered Reality | Elegia | Laughing Osiris | Senary |
| Alternate Realities | 1130 Club | Leprechaun | Sentinel SF |
| Alternaties | Embelyon | Les Spinge | Seventh Dimension |
| Alternative Coordinates | Empire for the SF Writer | Lethe | The Seventh Seal |
| Anomaly | Entropy | Lighthouse [1960s] | Severed Tales |
| Anotherealm | Erotic Horror & Fantasy Magazine | The Little Corpuscle | SFanzine |
| Antares | Escape [1930s] | The Looking Glass | Shadowdance |
| Anthro | Escape Velocity | Lost Pages | Shadowland [1950s] |
| Antithesis [1973] | Eternity | Lost Worlds | Shadowland [1990s] |
| Apocalypse Fiction | Ethereal Gazette | Lovecraftiana | Shiny |
| Appalling Stories | Eulogy | Low Orbit | Shiver |
| Arcana | Eusifanso | Lunar Castles | Si-Fan |
| Arioch | Event Horizon [1987] | Macabre Tales | Silver Blade |
| Art & Story | Exile [1960s] | Mad Scientist Journal | Sinfully Twisted |
| ASFO | Expressions of Dread | Mainstream | Sinister Tales |
| Asmodeus [1969] | Extro [1980] | The Many Worlds of Jack Vance | Skewed |
| Astonishing Stories [1935] | Eye of Newt | Maplecade | Sky Hook |
| Astounding Tales | Eye to the Telescope | Marginal Boundaries | S1ngularity |
| Athene | Fabulist [2009] | Mars! | The Sockdolager |
| Atomjack | Fadaway | The Marvellous Magazine | Sol Reader |
| Aurora Speculative Feminism | Fairy Tale Review | The Masked Spaceman | Sonar4 |
| Auslander | Fanatic | Masque (UK) | The Southern Star |
| Avatar | Fandom Unlimited | Meshuggah | Space Gamer/Fantasy Gamer |
| Avesta | Fanomena | Midnight Wine | Spaceports and Spidersilk |
| Banana Skins | Fan Slants | Mindflights | Space Squid |
| Banana Wings | Fantasia [1941] | Mindscapes | Spacesuits and Sixguns |
| Bane | Fantasia [1951] | Mirage | Space Tales |
| The Banshee | Fantasite | Miriad | Spaceteer |
| Barbarian Scroll | Fantast Sidetrack | Mirth and Irony | Spaceways [1996] |
| Bardic Runes | Fantasy Annual [1948] | The Miskatonic | Spearhead |
| The Barsoomian | Fantasy Collector's Annual | Modern Mythology | Spectra-Foundation SF & Fantasy Mag |
| Bar Trek | Fantasy Digest | Monomyth | Spectra Magazine |
| Basement Stories | Fantasy Fiction Field | The Monsters Next Door | Speculation |
| Beabohema | Fantasy Jackpot | Moondust | Speculative Fiction and Beyond |
| Betelgeuse | Fantasy Times | Morgan Smith | Speculon |
| Bête Noire | Fantazone | Moslem in Cambridge | The Specusphere |
| Bewildering Stories | Fanvariety | The Multiversal Scribe | SPGA Showcase |
| Beyond [1943] | Farrago | Multiverse Magazine | Staffs and Starships |
| Beyond the Moon | Fear and Trembling Magazine | Muse Fantastique | The Stake |
| Bite Me Magazine | FemSpec | Muzzy | The Standing Stone |
| Black Flames | Fiction Inferno | Mythos | Stardust [1960s] |
| Black Hole | Fifth Di... | The NASFA Shuttle | Starlight |
| The Black Lily | Flapperhouse | Nebula [1950] | Starlit Fantasy |
| Black Moon | Flash Fantastic! | Nebula [1970] | Steampunk Tales |
| Black Oracle | Flashing Swords | Necrography | Stellarite |
| Black Skull Magazine | Fogfire | Necrophantasy | STFanatic |
| Blood from 'Stones | Foma | Neometropolis | Stone Telling |
| Bloodlines | Fools Motley Magazine | Neverary | Straitjacket |
| Bloodrake | Fortean Bureau | Neverworlds | Strange Aeons [1990s] |
| The Blue Lady | Foundation | New Realm | Strange Aeons [2010] |
| Bone Chilling Tales | Foxfire | New Venture [1975] | Strange Brew |
| Bone Marrow Review | Franson's | New Witchcraft | Strange, Weird and Wonderful Magazine |
| Brillig | Freedom Fiction Journal | New Words | Strange Wonderland |
| Bulletin of Terrestrial Fantascience Guild | F(r)iction | Next Phase | Strix |
| Burroughs Bulletin | FTL Science Fiction | Nexxus | The Stylus [1993] |
| Byzarium | Full Moon S.F. | Night Dreams | Styx |
| Cabal Asylum | Fusion Fragment [2007] | The Nightmare Express | Sumer Morn |
| Cactus | Future Focus | Nightmares Quarterly | Sun Spots |
| Camber | Futurian War Digest | Nightside | Surprising Stories |
| Canadian Fandom | Futurismic | Night Views | The Sword Review |
| Canticles from Labowitz | Garage Floor | Nightworld | Swords and Sorcery Magazine |
| Catenary Tales | Gathering Darkness | Niteblade | Symphonie's Gift |
| Cats with Wings | Gauntlet! The Magazine of Heroic Tales | The Nocturnal Lyric | Syzygy |
| Cemetery Moon | genrEzone | Nomad | Tabebuian |
| Censored | Giallar | Not at Night | Talers Tales |
| Centauri | Glutonlumps Chilling Tales | Nova [1941] | Tales from Texas |
| Challenger | Goblin Fruit | Nova [1972] | Tales of Blood and Roses |
| Chanticleer | Golana | Nova [1989] | Tales of Horror and Damnation |
| Chaos Theory: Tales Askew | Golden Atom | Novae Terrae | Tales of the Episco Pals |
| The Chigger Patch of Fandom | Golden Visions Magazine | The Nucleus | Tales of the Grotesque and Arabesque |
| Chimaeran Review | Goodwitch Stories | Nuketown | The Tale Spinner |
| Chronicle | Gothic Light | Nu Ormenel Collected | Tangent [1976] |
| Ciln | Granfalloon | Odd Tales of Wonder Magazine | Terraform |
| Cinquefoil | Graveyard Rendezvous | Of Unicorns and Space Stations | Terror |
| Citadel | Grimoire [1993] | Ogre | Terror Hunters Journal |
| The City Morgue | Grok | Old Bones | The Thing |
| Clarges | The Grotesque [1940s] | Omnifan | Third Order |
| The Comet (fnz) | Grue [1953] | Omni Online | Thirteen Magazine |
| The Communicator | Gryffon's Star | The Oracle [1982] | This Way Up |
| Concept Sci-fi E-zine | Grymalkin | Orion Science Fiction | Tiamat |
| Cosmic Speculative Fiction | Gryphonwood | The Orphic Chronicle | TiconderogaOnline |
| Coyote Wild | Hands in the Dark | Ouroboros | Time Travel Tales |
| Crabapple | Harbinger [1975] | The Outlander | Tiofart |
| Crifanac | The Hardcore | Outside | TLMA |
| Cyberpulp Magazine | Harsh Reality | Outsider | Tomorrow Magazine [1970] |
| Cygni | Haunted Journal | Pages [1988] | Toward Tomorrow |
| The Cygnus Chronicler | Heart Attack | Pan Demos | Tower of Light |
| The Daily Phantagraph | Heliocentric Net | Pantechnicon | Trail of Indiscretion |
| Damned Thing | Heliophobe | Papyrus [1999] | Transmission |
| Dark Energy | Hocus | Paradox [1942] | Troat |
| Dark Infinity | Holier Than Thou | Parageography | The Tryout |
| Dark Moon Rising | Horizons (fnz) | Parlour Papers | TSAT (Transformation Stories) |
| Dark Muse | Horrorfest | Pegasus Online | Twilight Garden |
| Dark's Art Parlour | The Horror Fiction Review (fnz) | Peridot Books | Twilight Times |
| Dark Side | The Horror Zine | The Periodical Lungfish | Twin Cities SF & Fantasy Magazine |
| Dark Star | The H.P. Lovecraft Fanzine | Phantasia | Twisted Dreams Magazine |
| Dark Tome | Hugin and Munin | Phenomena | Ultraverse |
| Dark Visions | Hyphen [1952] | Phile | Undinal Songs |
| Darwin's Evolutions | Ibidem | Piffle | Universe Pathways |
| Daughters of Nyx | Ibn Qirtaiba | Planet Magazine | Usok |
| Dead Letters | If! (fnz) | Planet Relish | Usva International |
| Deadspawn | IFA Review | Pluto | Utopian |
| Demensions | Illumen | Polaris [1980] | Vamperotica Magazine |
| Dementia 13 | Imagination [1971] | Polluto | The Vampire Journal |
| Descend | Imagination [1990s] | Popular Music & Science-Fiction Journal | Vanations |
| Destiny [1991] | Imaginative Fiction | Pornographic Onion | The Velvet Vampyre |
| Dianoura | Incredible | Port Iris | Visionary Tongue |
| Diaspar | Infinite Edge | Procyon | Vortex Temporum |
| Diehard | Infinity [1970] | Proteus [1966] | Waxen Wings and Banana Skins |
| A Different Path | Infinity [1987] | Psychic Dimensions | Weird Space |
| Digital Catapult | Infinity Ltd. | Pulsar! | Whispers from the Dark |
| Digital Dragon | Inside (Science Fiction) | Quantum | White Dwarf |
| Digressions | Interstellar Fiction | Quantum Kiss | White Wolf |
| Dipple Chronicle | InterText | Quantum Muse | The Wolverine |
| Distant Worlds | In the Shadow of the Monolith | Radius | Wotta World |
| Don-o-saur | Invisible Stories | Realm of Fantasy | Would That It Were |
| Doorways | Is | Redshift | Yandro |
| Double:Bill (fnz) | Ixxis | Renaissance | Yawning Vortex |
| Dragonlaugh | Jackhammer E-zine | Revolution Science Fiction | Ye Yowlings of Yog-Sothoth |
| Dragonlore | Janus | The Richard S. Shaver Magazine | Zenith (Speculation) |
| Dragons, Knights and Angels | Jayland Unlimited | Rictus | The Zobee |
Since the advent of the Internet, a number of websites have published original fiction online as individual short stories, sometimes on a regular basis and sometimes on a rather more "ad-hoc" basis. In the initial confusion between traditional "print" magazines and the newer "digital magazines" there was a regrettable tendency to classify anything published online as being a magazine and a number of "titles" crept into earlier views of the Science Fiction Index even though they couldn't conceivably be regarded as magazines. Rather than "lose" the data already entered, those already entered into the index will continue being listed as magazines until such time as the indexes provide alternative support for this sort of data, but have been moved to the Fictionmags Index for convenience. The "known" publishers affected by this are listed below (with hyperlinks to the entry in the Fictionmags Index where relevant).
| AE: The Canadian Science Fiction Review | Daily Science Fiction | Little Blue Marble | Sci Fiction |
| The Arcanist | Eclipse Online | Mad Scientist Journal | Strange Constellations |
| Black Gate Online | Enigmatic Electronic | Mysterion | Terraform |
| Brain Harvest | |||
| Cemetery Dance Online | Event Horizon (1998) | Persistent Visions | Tor.com/Reactor |
| Cosmic Roots and Eldritch Shores | GigaNotoSaurus | Postscripts to Darkness |