Using fluoroscopic guidance, polyethylene biliary stents are replaced endoscopically or percutaneously when bile duct stenosis recurs. To improve the sensitivity of conventional biliary cytology, we examined cells recovered from removed stents. Biliary stents removed endoscopically from each of 11 patients were rinsed with saline; next, the rinse was centrifuged and the sediment smeared and Papanicolaou stained. Three patients with choledocholithiasis had biliary stent replacement cytology (BSRC) to exclude a neoplastic etiology. Eight patients with clinicoradiologic evidence of hepatobiliary or pancreatic carcinoma had BSRCs performed for pathologic documentation of carcinoma. BSRC from six of eight patients with clinicoradiologically malignant biliary strictures contained malignant cells, predominantly in loose clusters, but also singly (sensitivity 75%, specificity 100%; positive predictive value 75%, negative predicative value 60%). Reparative epithelial atypia was also present in all cases. BSRC from two patients with clinicoradiological evidence of carcinoma of the biliary region and from three with choledocholithiasis contained only bile pigment, leukocytes, and benign epithelial cells. The sampling of cells which have accumulated on, or in biliary stents, improves the sensitivity of biliary cytology. This is most applicable when 1) a patient is inoperable, 2) tissue biopsy is neither feasible nor diagnostic, 3) prior brush, suction, percutaneous, or endoscopic needle aspiration cytology is inconclusive, and 4) permanent metal stent is needed.