Pentastarch is a colloid that is chemically similar to Hetastarch. It has a shorter half-life (12 hr), and produces volume expansion at least 1.5 times the administered volume. We compared Pentastarch to Ringer's lactate in 41 patients (21 Pentastarch, 20 Ringer's lactate) presenting with hemorrhagic shock. The groups were similar in age, sex, race, and type of injury. Significantly less volume of Pentastarch was required initially to resuscitate to a normal blood pressure and urine output than Ringer's lactate (P < 0.005). Coagulation parameters (prothrombin time, partial thromboplastin time, fibrinogen, and factor VIII) were measured for 48 hr post-resuscitation, and no abnormalities were noted in the Pentastarch group. Serum albumin was the same in both groups throughout the study period; however, serum colloid oncotic pressure was elevated at 1 hr post-resuscitation in the Pentastarch group (P < 0.005). There was no difference in ventilatory parameters, blood gases, pulmonary function tests, ventilator days, or hospital days between the two groups. We conclude that Pentastarch is safe and effective for the initial resuscitation from hemorrhagic shock.