Methylprednisolone sodium succinate (MPSS) was given to 50% of patients undergoing coronary artery bypass graft in a 50-patient double-blind clinical study to ascertain the beneficial effects of this glucocorticoid in decreasing ischemic injury to the heart. MPSS (1 gm) was given intravenously at the start of cardiopulmonary bypass and another gram was given during the course of the open-heart procedure. Steroid-treated patients demonstrated a favorable response compared to placebo-treated controls in a variety of physiologic variables: Bypass graft flow rates measured prior to operative closure were 51-62% greater; urine output in the first 24 postoperative hours was 67% higher; fewer abnormalities were found in both chest x-ray and microbiology results. Thus, methylprednisolone sodium succinate treated patients exhibited more favorable trends for all critical variables measured.