The clinical significance of dysplasia and precancerous lesions of the cervix in pregnancy, frequency, age distribution and etiological factors is demonstrated based upon the clinical material of the Department of Obstetrics and Gynaecology of the University of Tübingen from 1970 to 1984. The diagnostic and therapeutic guidelines (cytology, colposcopy, histology by biopsy, conisation or hysterectomy) during pregnancy and associated problems are presented in detail. From a total of 168 patients included in the study, 128 revealed the histological classification Pap III/IIID, 38 Pap IVa/b and 2 cases Pap V. Histological carcinoma in situ was verified in 16 cases, microinvasive carcinoma in 6 cases and in 4 cases invasive cancer. From the data obtained, the following conclusions can be drawn: 1. Many of the dysplastic lesions of the cervix in pregnancy are found accidentally because of the limited participation of the patients in the routine cancer screening programme. 2. The precancerous lesions, even unfavourable stages, increase markedly in pregnancy. There is a shift towards younger women. 3. The known risk factors for cervical pre-invasive and invasive cervical abnormalities are confirmed. 4. For the management of cervical dysplasia in pregnancy it could be concluded, that observation by cytology and colposcopy should be done in cases with Pap III/IIID. In cases with Pap IVa/b, careful observation is mandatory, also by biopsy. Doubtful findings require conisation. Generally, this is also possible in pregnancy without complications. If invasion is excluded, an observant attitude may be adopted until delivery.(ABSTRACT TRUNCATED AT 250 WORDS)