Three patients with severe pre-eclampsia-toxemia were studied with thermodilution tip pulmonary artery catheters. All patients were delivered by cesarean section with general anesthesia and endotracheal intubation. The left ventricular stroke work indices (LVSWI) of these patients were higher than those of normal nonpregnant subjects. There was no evidence of myocardial depression in terms of either cardiac index or the LVSWi-pulmonary capillary wedge pressure (Frank-Starling) relationship. Pulmonary arteriolar resistance (PAR) was found to be within or below the normal nonpregnant range, suggesting that in severe toxemia the pulmonary vasculature is not involved in a primary vasospastic process. At delivery a rise in cardiac index (CI) and mean pulmonary capillary wedge pressure (PCWP) occurred. The PCWP was higher in the postpartum period than prior to delivery. This was felt to represent an increase in circulating blood volume. The therapeutic significance of these findings is discussed.