We prospectively collected brushings and bile for cytology in 30 consecutive patients with bile duct strictures (17 malignant, 13 benign) who were assessed by endoscopic retrograde cholangiography. When appropriate, the cellular debris on stents that were removed from individuals who were managed with these devices was evaluated for malignant cells as well. Our aim was to assess the value of these endoscopic cytotechniques for making a diagnosis of obstructing cancer of the biliary tract. A cumulative total of 78 specimens were obtained. Overall, sensitivity was highest for stent (36%) and brush (33%) cytology, compared with results obtained from bile (6%). If the results for all methods are combined, 47% of patients with cancer (eight of 17) could be diagnosed by one or more cytological technique. There were no false-positive results (specificity, 100%). Our results show that brush and stent cytology are nearly equivalent for detecting cancer, but because a diagnosis is delayed until the endoprosthesis is removed (mean 3.4 months), the brush technique is preferred. Results for bile cytology are marginal. Specificity for these cytotechniques is high; therefore, a positive result by any method is sufficient evidence for cancer, and other invasive diagnostic procedures are unnecessary.