Previous clinical evaluation of FK506 in renal transplantation has demonstrated equivalent patient and graft survival when compared with cyclosporine-based regimens. However, lower steroid and anti-hypertensive mediation requirements and lower serum cholesterol levels have been seen in patients receiving FK506. In August, 1991, a prospective, randomized trial was begun, comparing FK506/prednisone with FK506/azathioprine/prednisone. Two-hundred-and-four adults were entered into this trial between August 1, 1991, and October 11, 1992. The mean recipient age was 43.8 +/- 13.7 years, with a range of 17.6-78.0 years. Sixty-one (30%) recipients received a 2nd, 3rd or 4th transplant, while 35 (17%) had a PRA greater than 40% at the time of transplant. Thirty-three (16%) of the transplants were in recipients over 60 years of age, Thirteen percent of the kidneys were from living donors; 13% of the cadaveric kidneys were from pediatric donors less than 3 years of age and were transplanted en bloc. The mean cold ischemia time was 31.4 +/- 8.4 hours, and the mean donor age was 34 +/- 2.10 years, with a range from 4 months to 75 years. With a mean follow-up of 9 +/- 4 months, the 1-year actuarial patient survival is 93%; for the two-drug group it is 95%, and for the three-drug group it is 91% (p = NS). One-year actuarial graft survival is 86%; in the two-drug group it is 90%, while in the three-drug group it is 82% (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)