In spite of the apparent simplicity in detection of dysplasias (cervical intraepithelial neoplasias or CIN I, II, or III) and cancer of the cervix, numerous epidemiologic, biochemical, cytologic and socioeconomic problems are involved. The purpose of this early detection is unquestionably sound, even if the efficiency seems not to achieve high levels in accordance to expectations concerning results and if the cost of reiterated cervical and vaginal scraping smears seems exorbitant. The financial constraints and some cost-effectiveness analyses have promulgated use of longer intervals between cytologic exams (Pap tests). Such an attitude is only acceptable if an improvement in quality and sensitivity of detection is likewise established: other factors such as variable biologic development of epithelial lesions of the cervix must be taken into account; and consideration of cytologic sensitivity of early detection with the difficulties encountered in definition and identification of groups of women at risk. The longer spread between Pap smears exposes some women to the danger of non-detection of certain dysplasias (CIN I, II, or III), rapidly developing carcinomas, and so they lose out on the benefits of an early diagnosis, limited, effective, and less expensive treatment.