The authors have been developing an electrohydraulic (EH) artificial heart system for total implantation. This system consists of intrathoracic ventricles, an abdominally placed EH actuator, flexible silicone oil conduits, externally coupled transcutaneous energy transfer (TET) system, transcutaneous optical telemetry (TOT) system, internal battery, and internal control drive unit. Fitting was evaluated in chronic animal experiments as a pneumatic system in 11 goats weighing 55.2 +/- 4.2 kg and 3 calves of 52.3 +/- 1.2 kg. The longest survival time in calves was 111 days, and that in goats was 51 days. The assembled EH pump was implanted in two goats of 49 and 50 kg as an acute experiment, and 4.2-6.7 L/min of cardiac output was maintained. For the TET system, an internal coil 3 cm in diameter was implanted to make an arch covered by skin. Electric energy was transmitted from the external to the internal coil, and energy of about 20 W was carried through wires to an external load. The DC-to-DC efficiency of the system was 76-83% for 40 days. The TOT system with internal light emitting diodes and external photodiodes also was evaluated in a goat. Disalignment of up to 12 mm was tolerated. Although more improvement is necessary, most of the components showed characteristics desirable for a totally implantable system.