Objectives: To determine prevalence and risk factors of sexually transmitted infections (STIs), HIV, and cervical neoplasia in women attending women's health clinics in Nicaragua, and to assess the potential impact of screening for these diseases. Methods: Consecutive women attending women's health clinics in different regions were interviewed and examined for STI, HIV, and cervical neoplasia. Results: Whereas only 30.4% of the 1185 participating women attended the clinics because of STI related complaints, 77.0% reported symptoms after probing. Clinical cervicitis was diagnosed in 32.8%, Chlamydia trachomatis in 4.1%, gonorrhoea in 0.4%, trichomoniasis in 10.2%. Antibodies for syphilis were found in 0.7%, for hepatitis B in 3.7%, and none were HIV seropositive. The STI prevalence was 21.8% in women attending with complaints, 17.3% in symptomatic women after probing, and 14.8% in asymptomatic women. Abnormal Papanicolaou (Pap) smears were found in 7.7%, with high risk human papilloma virus (HPV) types in almost 60%. Male promiscuity was associated with high grade squamous intraepithelial lesions (HSIL) and reported former screening was not shown to be protective. Young age and being employed were risk factors for C trachomatis. Conclusion: Nearly one out of five women attending women's health clinics in Nicaragua had an STI, and one out of 13 a precancerous lesion of the cervix. These clinics provide an opportunity to improve the reproductive health of women by probing for STI symptoms, especially in young women, and by offering cervical screening to casual attendees. Of concern is the high rate of cervical lesions in women with a screening history, underlining the need for proper quality control.