In 1993, the development began of a small axial flow blood pump, the DeBakey ventricular assist device (VAD). The material was recently converted to a titanium alloy, and a waterproof pump package was incorporated for long-term intracorporeal circulation. Thirteen intrathoracic implantations in calves were achieved. Nine animals survived the 2 week perioperative period and were supported for a range of 26-93 days. The first study had low flow due to poor anatomical fit of the straight cannula. In contrast, a curved cannula used subsequently provided a good anatomical fit with sufficient flow. Mean flow of 4.4 L/min was sustained with 9,900 rpm and required power was an average of 8.8 W. No thromboembolic evidences were observed in any case, and the plasma free hemoglobin level was maintained lower than 5 mg/dl, except in the early postoperative period. Three animals were terminated because of bleeding due to anticoagulant mismanagement. Electric interference (n = 1) and drive line breakage/fault (n = 2) were observed as device-related failures. Minor modifications were made to the drive line. In conclusion, the DeBakey VAD demonstrated adequate basic performance and biocompatibility. The highly reliable mechanical components and improved electrical parts are promising for a long-term implantable cardiac prosthesis.