To compare the ThinPrep Imaging System (Cytyc Corp., Boxborough Massachusetts, U.S.A) to manual screening in the detection of cervical squamous epithelial lesion (SIL). A total of 27,525 manually screened ThinPrep Pap tests were compared with 27,725 imaged ThinPrep Pap tests for: (1) diagnostic rates of atypical squamous cells of undetermined significance; atypical squamous cells of undetermined significance, cannot rule out high grade SIL (ASC-H); low grade SIL and high grade SIL (HSIL); (2) ASC/SIL ratio; (3) high-risk HPV positivity for ASC; and (4) biopsy follow-up for ASC-H and HSIL. There were significant increases in the percentage of cytologic diagnoses in all categories with the imager. The ASC/SIL ratios of both groups were comparable. There was a significant decrease in HPV positivity in the imager group of ASC. Biopsy results confirmed a significant increase in the detection of HSIL in both the ASC-H and HSIL groups of the imaged cohort. The ThinPrep Imaging System is significantly better than manual screening in the detection of cervical SIL.