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 | Dragons, Knights and Angels | Jackhammer E-zine | Redshift |
| Absent Willow Review | Dragonwings | Janus | Renaissance |
| Ad Astra [1965] | The Dream Cell | Jayland Unlimited | Revolution Science Fiction |
| Adbhut | Dream Quest | Jinnia Clan Journal | The Richard S. Shaver Magazine |
| Afterburn SF | Dream Scene | Jinx | Rictus |
| Agog | Duckspeak | Kasma SF Magazine | Schlock! Webzine |
| Aleph-Null | Ecce | Kenoma | Science*Fiction [1945] |
| Alien Culture | Eclipse [1966] | Kinda Kinky | Science Fiction Scout |
| Alien Landings | Eclipse [1970] | Klein Bottle | Scienti-Comics |
| Alien Skin | Edge of Twilight | Knights | Scifaikuest |
| alphaDrive | eFantasy | The Kore | SciFi Dimensions |
| Altair [1950] | Eldritch Science | Labyrinth Inhabitant | SciFi Freedom |
| Altered Reality | Electric Wine | Lakeside Circus | SciFi Paradox |
| Alternate Realities | Elegia | Laser & Sword Magazine | Sci-Fi Short Story Magazine |
| Alternaties | 1130 Club | Lathered in Crimson | Scorched Earth |
| Alternative Coordinates | Embelyon | Laughing Osiris | Scream Queens Illustrated |
| Anomaly | Empire for the SF Writer | Leprechaun | SDO Fantasy |
| Anotherealm | Entropy | Les Spinge | Senary |
| Antares | Erotic Horror & Fantasy Magazine | Lethe | Sentinel SF |
| Anthro | Escape [1930s] | Lighthouse [1960s] | Seventh Dimension |
| Antithesis [1973] | Escape Velocity | The Little Corpuscle | The Seventh Seal |
| Apocalypse Fiction | Eternity | The Looking Glass | Severed Tales |
| Appalling Stories | Ethereal Gazette | Lost Pages | SFanzine |
| Arcana | Eulogy | Lost Worlds | Shadowdance |
| Arioch | Eusifanso | Lovecraftiana | Shadowland [1950s] |
| Art & Story | Event Horizon [1987] | Low Orbit | Shadowland [1990s] |
| ASFO | Exile [1960s] | Lunar Castles | Shiver |
| Asmodeus [1969] | Expressions of Dread | Macabre Tales | Silver Blade |
| Astonishing Stories [1935] | Extro [1980] | Mad Scientist Journal | Sinfully Twisted |
| Astounding Tales | Eye of Newt | Mainstream | Sinister Tales |
| Athene | Eye to the Telescope | The Many Worlds of Jack Vance | Skewed |
| Atomjack | Fabulist [2009] | Maplecade | Sky Hook |
| Aurora Speculative Feminism | Fadaway | Marginal Boundaries | S1ngularity |
| Auslander | Fairy Tale Review | Mars! | The Sockdolager |
| Avatar | Fanatic | The Marvellous Magazine | Sol Reader |
| Avesta | Fandom Unlimited | The Masked Spaceman | Sonar4 |
| Banana Skins | Fanomena | Masque (UK) | The Southern Star |
| Banana Wings | Fan Slants | Meshuggah | Space Gamer/Fantasy Gamer |
| Bane | Fantasia [1941] | Midnight Wine | Spaceports and Spidersilk |
| The Banshee | Fantasia [1951] | Mindflights | Space Squid |
| Barbarian Scroll | Fantasite | Mindscapes | Spacesuits and Sixguns |
| Bardic Runes | Fantast Sidetrack | Mirage | Space Tales |
| The Barsoomian | Fantasy Annual [1948] | Miriad | Spaceteer |
| Bar Trek | Fantasy Collector's Annual | Mirth and Irony | Spaceways [1996] |
| Basement Stories | Fantasy Digest | The Miskatonic | Spearhead |
| Beabohema | Fantasy Fiction Field | Modern Mythology | Spectra-Foundation SF & Fantasy Mag |
| Betelgeuse | Fantasy Jackpot | Monomyth | Spectra Magazine |
| Bête Noire | Fantasy Times | The Monsters Next Door | Speculation |
| Bewildering Stories | Fantazone | Moondust | Speculative Fiction and Beyond |
| Beyond [1943] | Fanvariety | Morgan Smith | Speculon |
| Beyond the Moon | Farrago | Moslem in Cambridge | The Specusphere |
| Bite Me Magazine | Fear and Trembling Magazine | The Multiversal Scribe | SPGA Showcase |
| Black Flames | FemSpec | Multiverse Magazine | Staffs and Starships |
| Black Hole | Fiction Inferno | Muse Fantastique | The Stake |
| The Black Lily | Fifth Di... | Muzzy | The Standing Stone |
| Black Moon | Flapperhouse | Mythos | Stardust [1960s] |
| Black Oracle | Flash Fantastic! | The NASFA Shuttle | Starlight |
| Black Skull Magazine | Flashing Swords | Nebula [1950] | Starlit Fantasy |
| Blood from 'Stones | Fogfire | Nebula [1970] | Steampunk Tales |
| Bloodlines | Foma | Necrography | Stellarite |
| Bloodrake | Fools Motley Magazine | Necrophantasy | STFanatic |
| The Blue Lady | Fortean Bureau | Neometropolis | Stone Telling |
| Bone Chilling Tales | Foundation | Neverary | Straitjacket |
| Bone Marrow Review | Foxfire | Neverworlds | Strange Aeons [1990s] |
| Brillig | Franson's | New Realm | Strange Aeons [2010] |
| Bulletin of Terrestrial Fantascience Guild | Freedom Fiction Journal | New Venture [1975] | Strange Brew |
| Burroughs Bulletin | F(r)iction | New Witchcraft | Strange, Weird and Wonderful Magazine |
| Byzarium | FTL Science Fiction | New Words | Strix |
| Cabal Asylum | Full Moon S.F. | Next Phase | The Stylus [1993] |
| Cactus | Fusion Fragment [2007] | Nexxus | Sun Spots |
| Camber | Future Focus | Night Dreams | Surprising Stories |
| Canadian Fandom | Futurian War Digest | The Nightmare Express | The Sword Review |
| Canticles from Labowitz | Futurismic | Nightmares Quarterly | Swords and Sorcery Magazine |
| Catenary Tales | Garage Floor | Nightside | Symphonie's Gift |
| Cats with Wings | Gathering Darkness | Night Views | Syzygy |
| Cemetery Moon | Gauntlet! The Magazine of Heroic Tales | Nightworld | Tabebuian |
| Centauri | genrEzone | Niteblade | Talers Tales |
| Challenger | Giallar | The Nocturnal Lyric | Tales from Texas |
| Chanticleer | Glutonlumps Chilling Tales | Nomad | Tales of Blood and Roses |
| Chaos Theory: Tales Askew | Goblin Fruit | Not at Night | Tales of Horror and Damnation |
| The Chigger Patch of Fandom | Golana | Nova [1941] | Tales of the Episco Pals |
| Chimaeran Review | Golden Atom | Nova [1972] | Tales of the Grotesque and Arabesque |
| Chronicle | Golden Visions Magazine | Nova [1989] | The Tale Spinner |
| Ciln | Goodwitch Stories | Novae Terrae | Tangent [1976] |
| Cinquefoil | Gothic Light | The Nucleus | Terraform |
| Citadel | Granfalloon | Nuketown | Terror |
| The City Morgue | Graveyard Rendezvous | Nu Ormenel Collected | Terror Hunters Journal |
| Clarges | Grimoire [1993] | Odd Tales of Wonder Magazine | The Thing |
| The Comet (fnz) | Grok | Of Unicorns and Space Stations | Third Order |
| The Communicator | The Grotesque [1940s] | Ogre | Thirteen Magazine |
| Concept Sci-fi E-zine | Grue [1953] | Old Bones | This Way Up |
| Cosmic Speculative Fiction | Gryffon's Star | Omnifan | Tiamat |
| Coyote Wild | Grymalkin | Omni Online | TiconderogaOnline |
| Crabapple | Gryphonwood | The Oracle [1982] | Time Travel Tales |
| Crifanac | Hands in the Dark | Orion Science Fiction | Tiofart |
| Cyberpulp Magazine | Harbinger [1975] | The Orphic Chronicle | TLMA |
| Cygni | The Hardcore | Ouroboros | Tomorrow Magazine [1970] |
| The Cygnus Chronicler | Harsh Reality | The Outlander | Toward Tomorrow |
| The Daily Phantagraph | Haunted Journal | Outside | Tower of Light |
| Damned Thing | Heart Attack | Outsider | Trail of Indiscretion |
| Dark Energy | Heliocentric Net | Pages [1988] | Troat |
| Dark Infinity | Heliophobe | Pan Demos | The Tryout |
| Dark Moon Rising | Hocus | Pantechnicon | TSAT (Transformation Stories) |
| Dark Muse | Holier Than Thou | Papyrus [1999] | Twilight Garden |
| Dark's Art Parlour | Horizons (fnz) | Paradox [1942] | Twilight Times |
| Dark Side | Horrorfest | Parageography | Twin Cities SF & Fantasy Magazine |
| Dark Star | The Horror Fiction Review (fnz) | Parlour Papers | Twisted Dreams Magazine |
| Dark Tome | The Horror Zine | Pegasus Online | Ultraverse |
| Dark Visions | The H.P. Lovecraft Fanzine | Peridot Books | Undinal Songs |
| Darwin's Evolutions | Hugin and Munin | The Periodical Lungfish | Universe Pathways |
| Daughters of Nyx | Hyphen [1952] | Phantasia | Usok |
| Dead Letters | Ibidem | Phenomena | Utopian |
| Deadspawn | Ibn Qirtaiba | Phile | Vamperotica Magazine |
| Demensions | If! (fnz) | Piffle | The Vampire Journal |
| Dementia 13 | IFA Review | Planet Magazine | Vanations |
| Descend | Illumen | Planet Relish | The Velvet Vampyre |
| Destiny [1991] | Imagination [1971] | Pluto | Visionary Tongue |
| Dianoura | Imagination [1990s] | Polaris [1980] | Vortex Temporum |
| Diaspar | Imaginative Fiction | Polluto | Waxen Wings and Banana Skins |
| Diehard | Incredible | Popular Music & Science-Fiction Journal | Weird Space |
| A Different Path | Infinite Edge | Pornographic Onion | Whispers from the Dark |
| Digital Catapult | Infinity [1970] | Port Iris | White Dwarf |
| Digital Dragon | Infinity [1987] | Procyon | White Wolf |
| Digressions | Infinity Ltd. | Proteus [1966] | The Wolverine |
| Dipple Chronicle | Inside (Science Fiction) | Psychic Dimensions | Wotta World |
| Distant Worlds | Interstellar Fiction | Pulsar! | Would That It Were |
| Don-o-saur | InterText | Quantum | Yandro |
| Doorways | In the Shadow of the Monolith | Quantum Kiss | Yawning Vortex |
| Double:Bill (fnz) | Invisible Stories | Quantum Muse | Ye Yowlings of Yog-Sothoth |
| Dragonlaugh | Is | Radius | Zenith (Speculation) |
| Dragonlore | Ixxis | Realm of Fantasy | 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 |