ABSTRACTThirty‐eight donors were selected from 312 volunteers to be as nearly compatible as possible with the patient's HLA‐A and ‐B antigens.In addition to HLA‐A and ‐B, MLC test was performed between the patient and all but one of the 38 donors (Donor No. 35), and all 38 homografts were applied to the patient at once.The mean survival time of HLA‐A and ‐B‐identical grafts was better than two haplotype‐mismatched grafts. There were no clear differences between 0 and 1, or 1 and 2 haplotype‐mismatched grafts.No definite differences in the survival number at 21 days was observed between HLA‐A and ‐B‐identical grafts and 1 haplotype‐mismatched grafts. However, a significant difference was detected between (0+1) mismatched grafts and 2 mismatched grafts.We were not able to detect any effects of ABO blood antige