A retrospective study was done on women who had atypical Papanicolaou smears and were referred for immediate colposcopy. The smears were obtained during January 1985 to March 1989 at Edwards Air Force Base, California. Excluded from the evaluation were abnormal Papanicolaou smears with hyperkeratosis, parakeratosis and koilocytotic atypia suggestive of human papillomavirus (HPV) infection. The evaluation included colposcopy, colposcopically directed biopsies, endocervical curettage and repeat Papanicolaou smears. A total of 101 patients were included in the study. Cervical intraepithelial neoplasia (CIN) was seen in 29.7% (30 patients): 12.9% (13) CIN I, 12.9% (13) CIN II and 3.9% (4) CIN III. Carcinoma was seen in 3.9% (4) of the patients: 2.9% (3) was carcinoma in situ, and 0.99% (1) was invasive squamous cell carcinoma, stage IIb. HPV and dysplastic lesions were seen together in 19.8% (20) of the patients. HPV was seen alone in 45% (46). Twenty-one patients (20.8%) had no apparent lesions on colposcopy, although one developed microinvasive keratinizing squamous cell carcinoma within 36 months of colposcopy. Many significant lesions can go undetected for extended periods of time in women with atypical Papanicolaou smears, resulting in delayed management. Referral for immediate colposcopy is advocated strongly.