To investigate the value of acetic acid visualization of the cervix as an alternative to cytologic screening. A prospective study was conducted in a squatter area in Cape Town, South Africa, on 2426 women who underwent speculum examination, naked-eye inspection of the cervix after application of acetic acid, and cytologic smear. The smears were stained and processed at the screening site. Patients with a positive reading after acetic acid or a smear indicating a high-grade squamous intraepithelial lesion (SIL) were referred for immediate colposcopy, biopsy, and when indicated, treatment by large loop excision of the transformation zone. Therefore, histology was obtained on all patients with a positive acetic acid test or a positive cytology. Seventy-six women with positive reactions to acetic acid. Among the 2350 women with negative reactions, 254 had positive cervical smears; only 11 of these had histologic high-grade SIL. In contrast, 20 of the 61 women with positive cytology and positive acetic acid test had high-grade SIL on histology. Therefore, the acetic acid reaction enabled the observer to detect 20 of the 31 women (64%) who exhibited a high-grade SIL both on cytology and histology. In locations where access to cytopathology is limited, naked-eye visualization of the cervix after application of diluted acetic acid warrants consideration as an alternative in the detection of cervical premalignant lesions.