411 women who had dysplasia, selected from an ambulatory group as well as 240 women from a random control group were examined, by using cervical smears, which were initially diagnosed as human papilloma viruses-DNA (HPV-DNA) of the type 6/11, or 16/18, or 31/33/35. This was achieved by the in-situ nucleic acid hybridisation technique. The results of the HPV-DNA typing were tabulated with the cytological diagnosis (Munich Papanicolaou (Pap.) group-classification). The control group corresponding to Pap.Gr. I, and was HPV-DNA positive in 6 (2.5%) of the 240 cases. The group of 180 patients with a Pap.Gr. II showed a HPV-DNA positive result for 75 cases (41.7%); 57 of 99 cases (57.6%) occurred in Pap.Gr. IIID; 42 of 54 cases 77.8% (L) were found in Pap.Gr. IV (a/b), and 72 of 78 cases (92.3%) appeared in Pap.Gr. V. The HPV-DNA mixed infections became evident as the cellular dysplasia increased. The results of the HPV-DNA positive diagnosis clearly indicate a close correlation with the Pap.Gr.-classification. The HPV-DNA type 16/18 was most frequent in cervical carcinomas (Pap.Gr. V). The cyto-histological control of the 57 HPV-DNA positive cases of the untreated Pap.Gr. IIID showed a regression in 31.6% of the 18 cases after a period of 3 to 6 months (post HPV-DNA typing). These were histologically normal. In 33 cases (57.9%), there was a persisting Pap.Gr. IIID (CIN I/II) and in 6 cases (10.5%) a progredient correlation in Pap.Gr. IV a/b. The Pap. group IV (a/b) was histologically a CIN grade III.