All ages admitted. There is no content that would be objectionable to most parents. This is one of only two ratings dating back to 1968 that still exists today.
I may have been up really late at night, but I didn't mind 'Alien Species' at all. Its craftsmanship for such a cheap B-movie production was pretty good (although the special effects looked like they were created on a Nintendo or Sega Genesis, and then grafted onto the film), the script was interesting enough in the realm of 'alien hostile takeover' movies, and its pace never lagged for a second....
