Satire on the sexual seventies? Parable on man's growing devotion to science? Simple horror film? It just might be all three. You could also put this in the Invasion of the Body Snatchers or Living Dead mold, a group that never stops, you either become one or die. However you look at this movie, it is real fun. There are plenty of gore scenes, most featuring strange growths on people. Then, there is also a heaping helping of bare breasts. My favorite scene is where one of the hotel staff tricks a couple into a large room where a parasite orgy is going on. He undresses while sticking out his tongue. Now, that is scary. The sole weakness of the film is that it is seriously dated, some scenes are funny now simply because of people's clothing. But the best joke of the movie is intentional; when sex is the sickness, who doesn't want it?<br /><br />P.S. They Came From Within is the the best of titles, but It Comes From Within would have been better.