The simplest and broadest application of clinical exfoliative cytology has been in the diagnosis of carcinoma of uterine cervix, and a vast literature has accumulated concerning the value of it especially in unsuspected preclinical stage. As a means of determining the efficacy of the cervicovaginal smear, the results of smears from 166 women were reviewed, compared to the histopathologic studied. Conclusively the diagnostic accuracy of cervical cytology is high (92.7%) in various epithelial lesions such as dysplasia (91-94%), carcinoma in situ (87%), microinvasive (78%) and invasive(95-100%) carcinomas, and it appears to be also useful in the follow-up of patients with cervical dysplasia as well as cervical carcinoma treated by either surgery or irradiation. In addition, the interpretations of sources of cytologic error were made in individual cases.