OBJECTIVES: To review the literature on the role of oral sex in the transmission of non-viral sexually transmitted infections (STIs). METHOD: A Medline search was performed using the keywords oro-genital sex, and those specific to each infection. Further references were then taken from each article read. CONCLUSIONS: Oral sex is a common sexual practice between both heterosexual and homosexual couples. Oro-genital sex is implicated as a route of transmission for gonorrhoea, syphilis, Chlamydia trachomatis, chancroid, and Neisseria meningitidis. Other respiratory organisms such as streptococci, Haemophilus influenzae, and Mycoplasma pneumoniae could also be transmitted by this route. Fellatio confers risk for acquisition of infection by the oral partner. Cunnilingus appears to predispose to recurrent vaginal candidiasis although the mechanism for this is unclear, while a link between oro-genital sex and bacterial vaginosis is currently being studied. Oro-anal sex is implicated in the transmission of various enteric infections. In view of the increased practice of oral sex this has become a more important potential route of transmission for oral, respiratory, and genital pathogens.