Experimental studies have shown that antilymphocyte globulin combined with transfusion of donor-specific bone marrow cells can induce partial tolerance to allograft tissue. We have adapted these protocols to clinical use and present the results of 57 cadaveric renal allograft recipients who received Minnesota ALG followed by the transfusion of cryopreserved donor-specific bone marrow. A group of 54 patients received the contralateral kidney and similar immunosuppression without the marrow transfusion and serve as controls. Both groups received quadruple immunosuppression with MALG, cyclosporin, azathioprine, and prednisone. In the bone marrow group, after a 10-14 day induction course of ALG, cryopreserved marrow was transfused on the seventh day after the last dose of ALG. The median follow-up in both groups is 16 months, (range 2.5-33 months). Six grafts have been lost in the bone marrow group, (three rejections, 2 deaths [Cr 2.0, 2.3], 1 recurrent disease). In the control group 16 grafts have been lost (13 rejections, 3 deaths [Cr 1.7, 2.5, 3.0]). Five patients in the control group have biopsy-proved chronic rejection compared to one in the bone marrow group. 17 patients in the bone marrow group have been tapered off the prednisone, and three of these patients have had mild late rejection episodes without graft loss. The two groups were compared for differences in the number of rejection episodes, estimated renal plasma flow, glomerular filtration rate, and urine protein. No differences were found. The allograft survival of the bone marrow group was significantly greater (P less than .01) than the control group. The graft survival rates for the bone marrow group at 12 and 18 months were 90% (confidence limits [CL] 85-94) and 85% (CL 78-90), respectively. In the the control group the 12 and 18 month allograft survival rates were 71% (CL 63-78) and 67% (CL 58-74), respectively. The survival in the control group was similar to our overall transplant experience with quadruple therapy. Mixed lymphocyte culture analysis shows a trend to diminished donor-specific responsiveness in the bone marrow group. The use of cryopreserved donor-specific bone marrow is associated with improved allograft survival in cadaveric kidney allograft recipients. However, a more effective induction protocol is needed to reduce the overall number of rejection episodes.