Localized collections of bile within the peritoneal cavity, "biloma," may occur after surgery or trauma and are readily detected by sonography and computed tomography. Eleven cases in which the diagnosis was confirmed by percutaneous needle aspiration and treatment carried out by radiologic catheter drainage are reported. Specific identification of bile was made by visual inspection, initial rapid dip-stick (Multistix) technique, and formal chemical analysis. Evidence of continued free bile leak included a positive technetium HIDA scintigram and copious amounts of bilious catheter drainage over a prolonged period. Unexpected clinical features of biloma included presentation as a pyogenic subhepatic abscess in four (36%) of 11 cases, localization of the biloma collection in the left upper abdomen despite surgery on the right side in four (36%) cases, and the presence of an active bile fistula in five (45%) cases. Percutaneous radiologic catheter drainage provided adequate therapeutic drainage in all but two patients in whom a continuing active bile leak eventually required surgical correction.