This study evaluates the effects of 30 mg/kg methylprednisolone (MP) administered to eight trauma patient over a 30-minute period during initial resuscitation. Vascular pressures, cardiac index (CI), left ventricular stroke work index (LVSWI), systemic (SVR) and pulmonary (PVR) vascular resistance, oxygen delivery (OD), oxygen consumption (VO2), physiological shunt (shunt), limb blood flow (LBF), limb-oxygen delivery (LOD), and limb oxygen consumption (VLO2) were calculated at control and 1, 2, 4 and 6 hours following MP administration. At 1 hour there was an increase in CI from 2.9 +/- 0.3 to 3.5 +/- 0.3 liters/min/m2 (P less than 0.01), in OD from 961 +/- 172 to 11067 +/- 148 ml/min (P less than 0.05), in VO2 from 178 +/- 16 to 220 +/- 16 ml/min (P less than 0.01), in shunt from 25 +/- 3% to 33 +/- 3% (P less than 0.05), and a decrease in SVR from 1187 +/- 98 to 1945 +/- 87, and in PVR form 222 +/- 22 to 178 +/- 18 dyne sec/cm5 (P less than 0.05). These values returned to control by 4 hours. In spite of a pulmonary wedge pressure (PWP) that did not increase form a control of 5 +/- 2 mm Hg, and a mean arterial blood pressure (MABP) that did not decrease from a control of 86 +/- 5 mm Hg, LVSWI increased significantly at 1 hour (P less than 0.01). LBF, LOD, and VLO2 decreased at 1 hour (P less than 0.05). Since increased cardiac output was associated with increased stroke volume and left ventricular stroke work index, but without an increase in preload (PWP) or a decrease in afterload (MABP), methylprednisolone(MP), in pharmacologic dosage appears to have a positive inotropic effect on the myocardium of trauma patients during resuscitation.