The blood pumping chambers and drive pump for a totally implantable artificial heart have been developed at the biomedical engineering laboratory. The drive pump is driven by an electric motor and provides alternate pumping of the blood pumping chambers. The blood pumping chambers are diaphragm pumps and have uniquely captured valves. The pressure waveforms produced by the blood pumping chambers were measured at 26, 52 and 78 beats per minute and the hemolysis caused by the blood pumps was measured under pressures likely to be encountered in the body. The average hemolytic index over the three trials was 0.041 for the right blood pumping chamber and 0.040 for the left blood pumping chamber. / M.S.