A total of 117 patients presenting with extrahepatic biliary strictures between 1981 and 1989 had 206 cytological examinations of the bile duct or bile (153 non-operative, 53 intraoperative) to establish the presence of malignancy. A final diagnosis of cholangiocarcinoma was made in 88 patients, with 29 patients having benign biliary strictures. The cytological techniques used were fine needle aspiration (n = 102) or brushing (n = 24) of the bile duct, or exfoliative cytology of bile (n = 80). Forty one patients with malignancy had two or more examinations with differing results between samples in 20 cases. The overall sensitivity was 72%. There was only one false positive result, giving a patient predictive value of positive cytology of 98%. Intraoperative cytology was more sensitive than non-operative examination (80% v 42%). Overall, the sensitivity of fine needle aspiration (67%) was greater than that of brush cytology (40%) or exfoliative cytology (30%). No complications were encountered. Cytodiagnosis of extrahepatic biliary strictures is a safe procedure which is not technically demanding, and as it has a high sensitivity and predictive value for positive cytology, cytological confirmation of malignancy should be sought in all clinically and radiologically suspicious cases.