Background Rituximab has greatly improved the outcomes of ABO‐incompatible living donor liver transplantation (ABO‐I LDLT). To clarify the optimal regimen for rituximab in adult ABO‐I LDLT, a multicenter study was conducted in Japan. Methods Clinical data of 33 adult patients undergoing ABO‐I LDLT at 15 centers in 2013 were retrospectively corrected. Results The targeted blood type was A1 in 18, B in 14, and AB in one patient. Rituximab was administered at 7 to 48 days before LT, at a dose of 375 mg/m2 in 12 patients, 500 mg in 15 patients, 300 mg in five patients, and 100 mg in one patient. Adverse effects of rituximab were tolerable. Overall 1‐year patient survival was 81%; antibody‐mediated rejection (AMR) occurred in three patients (9%), two of whom died. Rituximab dose was significantly lower in patients with AMR (P < 0.001, 137 ± 61 vs. 307 ± 66 mg/m2). Among rituximab dose (n = 28), local infusion (n = 11), splenectomy (n = 23), prophylactic intravenous immunoglobulins (n = 12), preoperative tacrolimus (n = 9), preoperative antimetabolites (n = 21), and plasmapheresis (n = 23), only rituximab dose was a significantly favorable factor for AMR (P < 0.001). Conclusion The use of rituximab at sufficient doses is recommended in adult ABO‐I LDLT. HighlightIn this multicenter study, Egawa and colleagues evaluated the association between rituximab dosage and successful desensitization to prevent antibody‐mediated rejection in ABO‐incompatible liver transplantation. They found that single administration of 500 mg or 375 mg/m2 was effective and that single administration of 300 mg or less could be insufficient.