OBJECTIVE. Although pathological discrepancy between Pap smear and biopsy is an accepted indication to perform a diagnostic loop electrosurgical excision procedure (LEEP), this procedure is not without complications. Our objective was to determine the incidence of cervical intraepithelial neoplasia (CIN) 2,3 and patient factors that increase the likelihood of detecting CIN 2,3. MATERIALS AND METHODS. We performed a retrospective chart review of patients who underwent a diagnostic LEEP for pathological discrepancy at a university-based colposcopy clinic. Pathological discrepancy is defined as a high-grade Pap smear with a colposcopically directed biopsy of CIN 1 or less. Demographic, cytological, and histological information were collected using a computerized database. The patients were divided into 2 groups (CIN 2,3 and CIN 1 or less) based on the pathology from the LEEP specimen. Patient factors were compared with final pathological results using χ test, Student t test, Wilcoxon rank sum test, and multivariate analysis as indicated. RESULTS. A total of 102 patients were identified. Seven patients had normal specimens, 3 had HPV changes, 25 had CIN 1, 29 had CIN 2, and 38 had CIN 3. Thirty-five patients (34%) had CIN 1 or less, whereas 67 patients (66%) had CIN 2,3. The 2 groups were comparable in terms of age (30.4 vs 28.1 years), parity (2.2 vs 1.9), and age of coitarche (16.3 vs 16.4 years). No statistical difference existed between the groups regarding race, smoking status, Pap smear, history of previous cytological abnormality, contraception method, number of previous sexual partners, and HIV status. The majority of patients (75%) had not undergone previous treatment of CIN. The CIN 2,3 group were more likely than the CIN 1 or less group to have had previous treatment or biopsy for CIN (66% vs 34%; p = .004). Univariate (p = .004) and multivariate (p < .001) analysis demonstrated previous treatment of CIN as the only significant factor predicting CIN 2,3. CONCLUSION. Two thirds of women undergoing a LEEP for pathological discrepancy between Pap smear and cervical biopsy will have CIN 2,3. Women that have had previous treatment of CIN are more likely to have CIN 2,3 detected on their LEEP specimen. ©2007The American Society for Colposcopy and Cervical Pathology.