The identification of permissible mismatches that do not impair graft survival might open exciting new possibilities which we should follow up. The data are preliminary, but if true, 50% of the patients in Eurotransplant could get a kidney with optimal graft survival. For sensitized patients we might consider adding a CTLp test, with and without CsA, to our serological crossmatch tests. This might be beneficial especially for interpreting noncurrent crossmatches. Information on the activation status of the donor-specific cytotoxic T cells on the day of transplantation (primed or not, CsA-resistant or not) provides additional information which could facilitate the decision of whether or not to accept a mismatched graft, even in case of donor-specific antibodies in historical sera. Under certain circumstances, haplotype-shared blood transfusions can induce transplantation tolerance. Time will tell whether the determination of the level of donor-derived soluble HLA antigens might be helpful in an early diagnosis of rejection. It might become a new device to monitor homograft reactivity and to identify the patients in whom immunosuppression could be decreased or even discontinued.