OBJECTIVE--To determine whether anal intercourse is a risk factor for anal HPV infection in women. DESIGN--Results derived from clinical examination, anal cytology and HPV DNA hybridisation were correlated with data obtained from a questionnaire administered to the patients at the time of their clinical examination. SETTING--A sexually transmitted diseases (STD) clinic in Sydney, Australia. SUBJECTS--31 women attending the clinic for HPV related problems. METHODS AND RESULTS--A thorough history was elicited from each woman followed by physical examination of the anogenital region. Cervical and anal scrapes were collected for cytology and HPV DNA hybridisation. Of the 15 women who practised anal intercourse, a total of 12 (80%) had either clinical or subclinical HPV infection. Seven had overt anal warts, situated either internally or externally in the anal canal; and further 5 women had evidence of subclinical HPV infection as determined by positive cytological and/or HPV DNA hybridisation results on their anal scrapes. The women who did not have a history of anal intercourse had a lower (7/16, 43%), but not statistically significant, rate of anal HPV infection: five had anal warts and two had subclinical evidence of infection. No correlations were found between anal HPV infection and genital (cervical, vulval or vaginal) HPV infection; nor between the HPV typing patterns of women in either group. CONCLUSION--The results obtained from these women do not indicate a close relationship between anal intercourse and the presence of detectable anal HPV infection.