OBJECTIVE To review the literature describing the use of the ThinPrep system in gynecologic cytology. METHODS Clinical trials of the ThinPrep Beta and the ThinPrep 2000 performed in the United States were reviewed. In each a single sample was used to first prepare a conventional slide and the remainder to perform a ThinPrep cervical cytologic test. Slides were examined in a blind fashion by cytotechnologists and classified according to Bethesda System terminology. RESULTS The ThinPrep test provided significantly more effective detection of low grade intraepithelial neoplasia or more severe diagnoses without loss of diagnostic specificity. The ability of the ThinPrep system to detect infection and reactive cellular changes was equivalent to or better than that of the conventional cytologic smear. Specimen adequacy was significantly enhanced with the ThinPrep test by reducing the number of cases classified as "Satisfactory but limited by...". CONCLUSIONS The ThinPrep test offers increased detection of cervical disease and a clear improvement in specimen adequacy. In addition to potentially lowering the false negative rate of cervical smears, collection of cells in liquid medium allows additional testing, such as human papillomavirus typing and computer imaging, to provide a more comprehensive diagnosis than that obtainable with the cervical cytologic test.