Our group has designed an air-powered, sac-type ventricular assist pump (VAP) that has a smooth polyurethane surface and Bjork-Shiley-type valves. This VAP has undergone extensive testing in calves and has been available for clinical use during the last 5 years. When properly employed, the circulatory support permitted immediate separation of the patient from bypass. Definite hemodynamic evidence of improved ventricular function has been observed during the period of unloading of the deranged ventricle by the VAP. However, during the first 3 years of our experience, the VAP was used in 11 patients with 1 survivor. During the last 2 years, specific attention has been directed to use of right, left, or biventricular assistance as indicated, to prompt application of the VAP when required, and to use of atrial rather than ventricular cannulation for VAP inflow. Accordingly, the survival rate over this 2-year period has increased to 50% (four of eight patients). The short-term assist pump is an important adjuvant for the surgeon who operates on seriously ill cardiac patients.