['To evaluate the influence of the anatomy of the right posterior bile duct (RPBD) of the donor on biliary complications in the recipients after living-donor liver transplantation (LDLT) using right hemi-liver grafts.', 'During living-donor right hepatectomy, the RPBD was often exposed to the dissection plane. We hypothesized that biliary complications after anastomosis were increased in these cases because of potential injury to the RPBD.', 'A total of 169 LDLTs using right hemi-liver grafts, with type I (typical) and type II (trifurcation) anatomy in conventional biliary classification, were retrospectively investigated. The patients were newly classified based on the confluence pattern of the RPBD. The patients were firstly divided into infraportal (IP, n = 12) and supraportal (SP, n = 157) types. SP type was subdivided into 3 groups: type A [ultrashort right bile duct (RBD), n = 20], type B (short RBD, n = 128), and type C (long RBD, n = 9). Type B was further subdivided into B-S (short caudal segment of the RPBD, n = 109) and B-L (long caudal segment of the RPBD, n = 19).', 'The biliary complication rate was 0% in type IP and type C, 40% in type A, 17.6% in type B-S, and 52.6% in type B-L (P < 0.01). In multivariate analysis, a new grouping of the RBD was a significant risk factor for biliary complications in LDLT.'] Is the right posterior bile duct anatomy of the donor important in biliary complications of the recipients after living-donor liver transplantation?