During a 3-year period, 167 women with an abnormal cytological finding (112-IIIA, 41-IIIB and 14-IV) were followed up cytologically and colposcopically in six weeks' intervals. They were evaluated during pregnancy, vaginal delivery and the puerperal period, and the cytological findings showed no progression of intraepithelial lesions into the invasive ones. Definitive postpartum pathohistological findings in 53 patients showed that 32 had in situ carcinoma, 12 severe and 7 light dysplasias, and 2 benign changes. The possibility of the false negative cytological assessments or invasive cervical carcinoma was excluded. Patholhistological and cytological findings matched in 77% of cases, whereas the degree of the former was lower in 21% and higher in 2% of the patients. In as many as 40.7% of patients the first post-delivery control cytological finding was negative. The reversible nature of these findings is emphasized, as well as the need to follow up these patients for at least one year.