During the last decade there has been an increasing interest in the use of the colposcope. A quality-control study for the evaluation and understanding of the limitations of cytology and colposcopy in our clinic is presented. The results in 132 patients are analysed and compared to previous reports from the literature. Cytologic results correlated with the histological diagnosis only in 47% of the patients. Colposcopically directed biopsies were accurate in 88.8% when the entire squamocolumnar junction was visualized. The accuracy of the directed biopsies in patients with unsatisfactory colposcopy was 58.3%. In the presence of a Gardnerella vaginalis cervicitis the colposcopic accuracy decreased to 70.9%.