The present study was undertaken to determine whether a biventricular bypass total artificial heart driven in an independent variable rate mode can maintain circulation in vital organs such as the brain and kidney. Special emphasis was placed on investigating flow distribution. Two pusher-plate pumps were used to bypass the right and left ventricles in 11 goats and 12 sheep with fibrillating hearts. The carotid artery and renal artery flows were then measured using an ultrasonic blood flow meter and the regional renal blood flow calculated using the hydrogen gas clearance method. Thirteen animals were kept alive for 24 hours in physiological hemodynamics but 10 animals died of shock within 24 hours. In the latter group, a decrease in the fractional distribution of flow to the kidney and renal cortex were observed. At a peak aortic pressure of less than 100 mmHg, the renal flow ratio was significantly correlated with the peak aortic pressure. It was thus concluded that the biventricular bypass total artificial heart operated in an independent variable rate mode maintains physiological circulation and is therefore able to substitute for native heart function in any situation.