Most of the above contributors have made valid points, and #9 pointed out that fantasy and science fiction utilize many of the same "plot types, character archetypes, and fantastical settings." Got it in one: they fall under the umbrella of "speculative fiction," as do dystopias, utopias, "doomsday" literature, alternate histories, much occult literature, paranormal romance, much horror fiction, "space opera," and much of myth and folklore. Speculative fiction may be loosely defined as the fiction of "what if?" What if the genders WERE equal? What if humans had metapsychic powers? What if FTL travel were discovered? What if NON-humanoid sentient races visited earth? What if plants were sentient? What if magic were real? What if females could be heroes instead of heroines? [Honest confession being good for the soul, I hereby confess that this "what if" has been a major focus of my reading, research, teaching, lecturing, and publishing.]

Yes, the post-WWII boom in science fiction DID appeal to a male audience and involve primarily male writers: we had a HUGE population of mostly male G.I.s whose view of the world was forever changed by the atrocities of WWII. A similar surge in speculative fiction occurred after Viet Nam, with a similar audience of traumatized veterans and their often-puzzled families and friends. But women were active in and before both surges, often under male pseudonyms; being constrained by gender is certainly NOT exclusive to female authors of speculative fiction, nor is it a recent situation. Such luminaries of speculative fiction as Alice Sheldon [James Tiptree], C.J.Cherryh, C.L. Moore, Megan Lindholm [Robin Hobbs], Jacqueline Lichtenberg [Daniel R. Kerns], Andre Norton [enotes has a superb article about her], Mickey Zucker Reichert, Anne Rice [A.N. Roquelaure], Chelsea Quinn Yarbro [Quinn Faucett], Jo Clayton, Julian May [Ian Thorne], Leigh Brackett [George Sanders], and even J.K. Rowling have written/published under either male or gender-neutral pseudonyms.

Julian May's magnificent "Saga of Pliocene Exile/Galactic Milieu" series, comprising a quartet, a trilogy, and a duology, proves definitively that women CAN handle "equipment" novels, and handle them with a rare flair for universe-building. Elizabeth Moon, Sherri S. Tepper, C.J. Cherryh, Melissa Scott, Jo Clayton, Leigh Brackett [she wrote the first draft of "The Empire Strikes Back"], Lois McMaster Bujold, Anne McCaffrey, Mercedes Lackey, Barbara Hambly, Sharon Shinn, Nancy Kress, Niccola Griffith, Vonda McIntyre, Patricia Kennealy-Morison, A.C. Crispin, and a host of others demonstrate that they can incorporate real technology into, and/or handle "equipment" gracefully, and/or interweave "hard" science with, their speculative fiction, seamlessly. Numerous women have written for such technology-intensive series as "Star Trek" and its descendents, "Star Wars" and its descendants, and "Quantum Leap."

I’ve said all that to say this: science fiction is MUCH less dominated by men than in the past -- and the genre has benefited greatly from its increased leavening by women writers.

It may have to do with the origin of the genre.  Remember that women haven't been socially accepted as authors for very long.  When women were allowed into the world of published literature, they were original confined to writing novels.  It was the men who had the freedom write anything they wanted.  It is no wonder then that the genre of sci-fiction has more male authors than female authors.  Now that times have changed, perhaps we will see more sci-fiction written by women. 

Fantasy fiction and science fiction, as genres, have often seemed to be nearly indistinguishable to me as they utilize many of the same plot types, character archetypes and fantastical settings. 

Yet the genre of fantasy seems to be more equally represented by male and female writers than science fiction. Can it be that the "equipment story" explains a real difference (or defines the difference) between these two very similar genres of fiction? One type of story-telling is interested in ships and tools and stuff and the other is less interested in them? 

I agree with #4. There's a genre that I think of as the Equipment Story. It's a tale that is highly dependent on weapons, transport vehicles, and other mechanical devices; this genre seems to be more commonly written by, and is generally more appealing to, men. It's not limited to science fiction - writers like Clive Cussler and Tom Clancy are very equipment oriented - but it's tough to write convincing science fiction without it.

On the other hand, here's a link to a rather lengthy list of female science fiction/fantasy writers. They are out there!

I agree with posts 4 and 5 - I think this is a function of a culture that, historically, has assumed girls and women aren't able to understand or use math or science so they are not educated in these fields, in the same way that girls and women seeking a career are guided into teaching or nursing or secretarial pursuits.

As more females become involved in science, technology, engineering, and math fields, I would hope we will see more feminine writers of science fiction.

I think it has to do with the historical development of Science fiction. This genre rose to its height of popularity during the post WWII period, a time of clear traditional roles for men and women. During this time, science fiction drew upon the cold war fears and new technology and rose to popularity. This was also a time when women were not encouraged to pursue math and science. Science fiction became the domain of male readers, and male writers. I think that over time while women have had more success in the real sciences, Science fiction is still being written toward a male audience.

I also wonder if it's the "science" part of science fiction that tends to attract male writers.  Women have traditionally been discouraged from scientific disciplines, and the name of the genre might have played a part in this.  There are, though, some great female science fiction writers, for example, Ursula LeGuin.  While I by no means have a sufficient sampling to make a definitive statement, it seems to me that there are far more male science fiction readers than there are female ones. 

I wonder if this will change as more women become interested in mechanical things.  After all, there is nothing about science fiction that demands that there be macho heroes.  There is a huge difference, for example, between Captain Kirk and Captain Picard in the Star Trek universe.  

In addition, there are plenty of women who write stories that are more of fantasy stories but that could be done as sci fi if they wanted to.  For example, Diana Gabaldon's time travelling "Outlander" series could work as sci fi too. 

I guess I think that it's really just inertia since we are not that far removed from a time in which women were really not "allowed" to be interested in a lot of the things that sci fi is about.

In general I agree with post #2. I would add that a lot of sci-fi involves heroic, sometimes macho, characters who are usually male. The genre developed that way, and that's more of a male-oriented area.

This very interesting question was posted by sugartween, as shown above. I believe it is worth discussion since there must be many different points of view. It does seem to be a fact that the field of science fiction is pretty much dominated by male writers. I don't know a whole lot about science fiction, but my impression is that men tend to be more interested in things and women tend to be more interested in human relationships. But maybe that is sexist. My answer is: I don't know.