Immune-related adverse events, including immune hemolytic anemia, have been reported in patients treated with immune checkpoint inhibitors. In particular, RBC autoantibodies are important because they can cause hemolytic anemia and interfere with pre-transfusion tests. On the other hand, there are few reports on the characteristics of RBC autoantibodies induced by immune checkpoint inhibitors in Korea. The medical history and laboratory results, including pretransfusion tests of ten patients treated with immune checkpoint inhibitors, were reviewed retrospectively. The median interval from the first administration of immune checkpoint inhibitors to the development of autoantibodies was 12 weeks. In eight patients, only cold autoantibodies were developed. Both warm and cold autoantibodies developed in one patient, and warm autoantibodies alone were detected in one patient.Of seven patients tested by a direct antiglobulin test, two were negative, and the remaining five were positive for IgG and negative for C3d. In conclusion, this study presented ten cases of autoantibody developments in patients treated with immune checkpoint inhibitors and the possible relationship between the immune checkpoint inhibitors and RBC autoantibody development. Further comprehensive studies will be needed to elucidate this relationship.