© 2017 American Cancer Society BACKGROUND: The objective of this study was to compare cervical high-grade squamous intraepithelial lesions subcategorized as cervical intraepithelial neoplasia-3 (CIN-3)–positive after a negative cytology result but positive for high-risk human papillomavirus (HR-HPV) testing to those with a negative HR-HPV test but positive cytology (atypical squamous cells of undetermined significance [ASCUS]-positive/HPV-negative) and to assess reasons for discrepancies. METHODS: The authors retrospectively analyzed women who underwent screening with cytology and HPV testing from 2010 through 2013. After a review of surgical specimens and cytology, discrepancies were classified as sampling or interpretation error. Clinical and pathologic findings were compared. RESULTS: In total, 15,173 women (age range, 25-95 years; 7.1% were aged < 30 years) underwent both HPV and cytologic testing, and 1184 (8.4%) underwent biopsy. Cytology was positive in 19.4% of specimens, and HPV was positive in 14.5%. Eighty-four CIN-3–positive specimens were detected, including 55 that tested ASCUS-positive/HPV-positive, 11 that tested negative for intraepithelial lesion or malignancy (NILM)/HPV-positive, 10 that tested ASCUS-positive/HPV-negative, 3 that tested NILM/HPV-negative, and 5 tests that were unsatisfactory. There was no significant difference between NILM/HPV-positive and ASCUS-positive/HPV-negative CIN-3 in terms of size, time to occurrence, the presence of a cytopathic effect, screening history, race, or age. Six of 11 NILM/HPV-positive cases were reclassified as ASCUS, indicating an interpreting error of 55% and a sampling error of 45%. No ASCUS-positive/HPV-negative cases were reclassified. Seven cases of CIN-3 with positive cytology were HPV-negative. CONCLUSIONS: There are no significant clinical or pathologic differences between NILM/HPV-positive and ASCUS-positive/HPV-negative CIN-3–positive specimens. Cytologic sampling or interpretation remains the main reason for discrepancies. However, HPV-negative CIN-3 with positive cytology exists and may be missed by primary HPV screening. Cancer Cytopathol 2017;125:795-805. © 2017 American Cancer Society.