The steroid-sparing effect and the use of concomitant medication during the treatment of liver transplant patients with the novel immunosuppressant FK 506 were evaluated within the European multicentre, randomized, parallel-group study in liver transplantation. Patients undergoing primary liver transplantation were randomized to treatment with FK 506 (n = 267) or with a cyclosporin-based immunosuppressive regimen (n = 273). The total cumulative steroid usage was significantly reduced in the FK 506 treatment group, which is likely to have resulted from the lower incidence of acute rejection in these patients. The number of patients receiving antidiabetic, diuretic and antihypertensive therapy did not differ between the two treatment groups, even though the incidence of diabetes mellitus and oliguria was significantly higher in the FK 506 group. It can, therefore, be assumed that in a number of such cases the severity of these events was very mild necessitating no specific therapy.