After heart transplantation, recipients frequently become obese. Although the cause is undoubtedly multifactorial, administration of corticosteroids may contribute to posttransplant obesity. To test this hypothesis, we retrospectively reviewed the change in body weight with respect to corticosteroid use after transplantation in all 110 recipients surviving 1 year in the UTAH Cardiac Transplant Program. Fifty-two recipients (47%, group 1) were unable to be withdrawn from maintenance corticosteroids, and 58 recipients (53%, group 2) were successfully withdrawn, the latter group requiring only cyclosporine and azathioprine long-term maintenance immunosuppression. The change in weight from the time of transplantation to 1 year after transplantation in group 1 was 8.7 +/- 1.1 kg; group 2 patients gained only 4.9 +/- 0.9 kg (p = 0.009). In conclusion, successful withdrawal of maintenance corticosteroids after heart transplantation decreased posttransplant weight gain, suggesting that posttransplant obesity is in part related to use of corticosteroids.