An evaluation was made of 457 colposcopically guided punch biopsies from patients with suspicious areas in the ectocervical mucous membrane showing leukoplakia, punctations , mosaic structures or atypical transformation zones. Intraepithelial cervical neoplasias could be demonstrated histologically in 56 cases (12.3%). Irrespective of the nature of the epithelial findings, the histological pictures correlated with colposcopic findings in 388 cases (84.9%) as far as epithelial structure, abnormal epithelial-stromal relations, keratoses and stroma alterations are concerned. The correctness of the colposcopic findings can be certified by precise formulation of these changes in the histological report. This additional information is offered to encourage more extensive use of the colposcope . Colposcopy, used routinely and independent of cytology, provides satisfactory quality control for cytology.