The complications of immunosuppresive therapy that occurred in a series of renal transplant patients presented were many. Of the total 28 renal transplants performed in Sarajevo, 25 were observed. These complications were diagnosed in 19 cases (6 of which exited), Death in each case was due to virual and not bacterial infection which occurred most often in the lungs. No urinary infections occured in any of these cases. The actual cause of death in most of the patients was most frequently due to pneumocystis and alveo-capillary block of the lungs which is very difficult to diagnose. When this complication presented itself the method of choice was rapid manipulation of the immunosuppressive therapy together with the administration of concentrated granulocytes which did not significantly impair the function of the grafted kidney in any of the cases save those with cortizone diabetes. High body temperature was also of diagnostic importance. The authors feel that quick action and accumulated clinical experience prevent the fatal outcome of many renal transplant patients with complications from immunosuppressive therapy.