Transplantation of kidneys bearing HLA antigens to which recipients have previously been exposed is generally avoided, and such prudence is a well-documented means of preventing early graft loss. Prior exposure and subsequent reactions can, however, take a wide variety of forms, and blanket avoidance may prevent many deserving patients from being transplanted. In our region, operating through a single tissue-typing laboratory, we follow a consistent policy of allowing retransplantation with kidneys bearing previous mismatches, provided no relevant antibody response has been detected. Twenty-one of 34 such transplants remain functioning at time periods ranging from 7 months to 7 years. Four were lost due to rejection within the 1st month, and the remaining 9 functioned for periods ranging from 2 months to 8 years. Three were lost for reasons other than rejection. Our antibody screening policy and our criteria for a negative crossmatch results in the exclusion of two-thirds of all repeat mismatch transplantations. The results indicate that in the remaining third, transplantation can be performed across a repeat mismatch with excellent long-term results, provided our defined crossmatch policy is adhered to strictly.