SummaryThe aim of the study was to establish the clinical value of Schiller's test in routine colposcopic examination of the uterine cervix. Colposcopy was carried out with the application of 3 per cent acetic acid followed by Lugol's iodine solution in 1554 consecutive patients. In 16 patients (1 per cent) a sharply outlined iodine-negative area was detected that could not be visualised with acetic acid alone. Histological examination of biopsy specimens from the iodine negative areas revealed ON 1 in two cases, flat condylomata in three cases, minor histological changes suggestive of human papillomavirus infection in six cases, non-specific inflammatory alterations in four cases; and normal epithelium in two cases. These results suggest that systematic use of Schiller's test in routine colposcopic examination of the uterine cervix may be of value.