Glucocorticosteroid, methylprednisolone sodium succinate (MPSS), 30 mg/kg of body weight, or dexamethasone sodium phosphate (DSP), 6 mg/kg of body weight, were given intravenously to 60 patients, divided into two groups of 30 45 minutes prior to cardiopulmonary bypass for coronary artery bypass. These two groups were compared with 30 patients in a control group receiving a placebo and undergoing the same surgery. The study was carried out in a double-lind fashion. Patients receiving MPSS had a significantly higher cardiac index in both the preoperative and postoperative periods. This was accompanied by a decreased peripheral resistance. Patients receiving either MPSS or DSP also showed some evidence for the "washout" phenomenon indicating the possibility of better microcirculatory flow. Gluconeogenesis may have been enhanced in both groups receiving MPSS or DSP, but the evidence was greater in thos patients receiving MPSS. There were no hospital deaths in any of the three groups totaling 90 patients.