The authors evaluated the effectiveness of 6% hydroxyl-ethyl starch (hetastarch) solution for treatment of hypovolemia in 46 critically ill patients. Thirty-two of the patients were studied retrospectively and in 14 patients, cardiopulmonary variables were prospectively measured. A total of 29 patients were in shock secondary to hypovolemia (13), sepsis (13), or myocardial infarction (3). Average hetastarch infusion volume was 829 and 842 ml, respectively, in prospectively and retrospectively studied patients, with maximum volumes of 2000–2500 ml infused over 48 h. Approximately 30% of 24 h fluid needs were supplied with colloids.Infusion of 500 ml of hetastarch in 14 prospective study patients was associated with increases in pulmonary artery wedge pressure (WP) from 9 ± 1.5 to 12 ± 2.1 mm Hg, cardiac index (CI) from 2.9 ± 0.2 to 3.5 ± 0.3 (p< 0.05) along with an increase in mean arterial pressure (MAP) from 87–99 mm Hg and reduction in arteriovenous O2difference [C(a-v)o2] from 4.9 to 4.2 ml/dl. Intrapulmonary shunt (Qsp/Qt) was similar (20 vs. 21% as were alveolar-arterial O2gradient [P(A-a)o2] (165 vs. 158 torr), whereas O2consumption (Vo2) increased from 224 to 247 ml/min. Immediate survival was 90% in shock patients and 100% in nonshock patients, whereas hospital survival was 65.5% and 88%, respectively. The authors conclude that hetastarch is an effective fluid for resuscitation of hypovolemic patients. This synthetic colloid does not appear to adversely affect pulmonary function.