In the period from March 1970 to April 1978, 176 kidneys from 137 cadaver donors were exchanged, on the basis of HLA matching, between transplant centres throughout Australia and New Zealand. The kidneys were preserved by simple ice storage or machine perfusion, and transported by air in chipped ice. Total ischaemia times ranged from 3.5 to 28.6 hours and immediate function occurred in 52% of cases. Graft survival was 62% at one year, 51% at three years and 47% at five years, the corresponding patient survival rates being 86%, 74% and 71%. An average of 1.4 antigens mismatched was achieved, and 59% of recipients received kidneys with zero or one antigen mismatched. These kidneys survived better than those with two or more antigens mismatched, the difference being 12% at one year, and rising to more than 20% at five years. The results confirm the practicability and potential value of the Organ Sharing Scheme, and indicate that effective sharing of kidneys on the basis of zero HLA mismatches could substantially improve the current success rate of clinical cadaveric renal transplantation.