Matched perianal swabs, rectal swabs, and faecal samples from a group of male homosexual patients attending a clinic for sexually transmitted disease were examined for the presence of group B streptococci (GBS). GBS recovery rates were as follows: perianal skin 31/115 (27%), rectal mucosa 18/72 (25%) and faeces 7/115 (6%). The recovery of GBS from faeces was similar to that obtained from faecal samples sent to the laboratory for routine investigation (5%). Although there was no difference in GBS recovery rates from rectal and perianal swabs, the latter did show heavier colonisation. These results suggest that gastrointestinal GBS carriage is mainly limited to the rectum and anal canal and that this may represent contamination from perianal skin.