The prevalence of sexually transmitted diseases (STD) among women visiting antenatal (ANC) and gynaecological clinics in Gondar, north-west Ethiopia, was investigated. Between April and August 1995, 728 women consented to enter the study. Prevalence rates were 5·9% (41/693) for chlamydial antigen in cervix, 18·8% (113/600) for syphilis (Treponema pallidum haemagglutination assay [TPHA]) and 25·3% (150/593) for HIV. Active syphilis (RPR)+, TPHA+ was detected in 7·4% (44/597). HIV infection rate was higher among women with higher age of first marriage and low gravidity. It was significantly associated with young age, urban residence, and presence of genital ulcer (odds ratio [OR]=6·3), and lymphadenopathy (OR=2·8) on examination. Women seropositive for syphilis had married at an earlier age, were significantly older and had changed husbands. Low gravidity and age <30 were independently significant risk factors for cervical chlamydial antigen positivity which was predominantly asymptomatic. Significant association was observed between HIV infection and syphilis (OR=2·6). Active syphilis was associated with chlamydial (OR=3·4) and HIV infection (OR=4·1). The rate of 23·4% and 15·1% of HIV seropositivity among ANC attenders and rural women respectively is an indicator of the rapid progression of the HIV epidemic in the area.