The mainstay of early diagnosis of CIN is exfoliative cytologic screening of the cervicovaginal area. The Achilles heel in this tremendously valuable screening process is the high false negativity rate. The false negativity rate can be diminished by rigid adherence to indications for screening, screening technique, proper interpretation and reporting, and utilization, where indicated, of adjunctive diagnostic methods such as multiple biopsy, colposcopy, and maintenance of the annual screening schedule in the majority of patients.