Background-Helical computed tomography performed after intravenous administration of a cholangiographic contrast material (HCT-cholangiography) may be useful for detecting bite duct stones in non-jaundiced patients. However, this method has never been compared with other non-invasive biliary imaging tests. Aims-To compare prospectively HCT-cholangiography and endosonography (EUS) in a group of non-jaundiced patients with suspected bile duct stones. Method-Fifty two subjects underwent both HCT-cholangiography and EUS. Endoscopic retrograde cholangiography (ERCP), with or without instrumental bile duct exploration, served asa reference method, and was successful in all but two patients. Results-Thirty four patients (68%) were found to have choledocholithiasis at ERCP. The sensitivity for HCT-cholangiography in stone detection was 85%, specificity 88%, and accuracy 86%. For EUS the sensitivity was 91%, specificity 100%, and accuracy 94%. The differences were not significant. No serious complications occurred with either method. Conclusions-HCT-cholangiography and EUS are safe and comparably accurate methods for detecting bile duct stones in non-jaundiced patients.