A total of 1580 new patients underwent colposcopic evalution in the Dysplasia Clinic at Nassau County Medical Center. Of these patients, 186 had abnormal Papanicolaou smears associated with pregnancy, 150 were referred because of in utero exposure to diethylstilbestrol, and 1244 were referred because of abnormal cervical cytologic smear or suspicious cervical or vaginal lesion. Further analysis of this latter group revealed that 1184 (95%) patients had satisfactory colposcopic evaluation, and directed biopsy showed the following: 10 cases of invasive cervical carcinoma, 9 of carcinoma in situ with microinvasion, 118 of cervical carcinoma in situ, 110 of severe dysplasia, and 424 cases of mild to moderate cervical dysplasia. All of these patients subsequently were treated accordingly. Evaluation of final histologic specimen revealed a very high correlation with colposcopically guided biopsies. In 54 patients, where colposcopic evaluation was unsatisfactory, diagnostic cold knife conization was performed. Final histologic diagnosis disclosed a more advanced lesion in 30 patients (or 56%) of this group. The result of this study shows that satisfactory colposcopic evaluation is a highly accurate method of evaluation of abnormal cervical and vaginal cytologic smear.