Nonanastomotic biliary strictures (NAS) are a serious complication after orthotopic liver transplantation (OLT). The exact pathogenesis is unclear. Purpose of this study was to identify risk factors for the development of NAS after OLT. A total of 487 adult liver transplants with a median follow-up of 7.9 years were studied. All imaging studies of the biliary tree were reviewed. Cholangiography was routinely performed between postoperative days 10-14 and later on demand. Localization of NAS at first presentation was categorized into 4 anatomical zones of the biliary tree. Severity of NAS was semiquantified as mild, moderate, or severe. Donor, recipient, and surgical characteristics and variables were analyzed to identify risk factors for NAS. NAS developed in 81 livers (16.6%). Thirty-seven (7.3%) were graded as moderate to severe. In 85% of the cases, anatomical localization of NAS was around or below the bifurcation of the common bile duct. A large variation was observed in the time interval between OLT and first presentation of NAS (median 4.1 months; range 0.3-155 months). NAS presenting early (< or =1 year) after OLT were associated with preservation-related risk factors. Cold and warm ischemia times were significantly longer in patients with early NAS compared with NAS presenting late (>1 year) after OLT (694 minutes vs. 490 minutes, P = 0.01, and 57 minutes vs. 53 minutes, P < 0.05, respectively), and early NAS were more frequently located in the central bile ducts. NAS presenting late (>1 year) after OLT were found more frequently in the periphery of the liver and were more frequently associated with immunological factors, such as primary sclerosing cholangitis, as the indication for OLT (24% vs. 45%, P < 0.05). By separating cases of NAS on the basis of the time of presentation after transplantation, we were able to identify differences in risk factors, indicating different pathogenic mechanisms depending on the time of initial presentation.