In the last 9 years, 30 patients received assisted circulation or a ventricular assist device after open-heart operations at the Heart Institute of Japan. After cardiovascular surgery, 9 of those patients underwent venoarterial bypass, 10 had biventricular bypass, 7 had left ventricular bypass, and the remaining 4 received a left ventricular assist device. Of the first 15 patients, only 3 (20%) were discharged from the hospital. In contrast, 7 (46.7%) of the last 15 patients were discharged without major complications. With respect to complications, bleeding and ventricular arrhythmia (immature weaning) decreased with low-heparinized isolated left ventricular supports. However, profound biventricular failure, infection, and multiple organ failure remain as possible complications with any type of assisted circulation. These results suggest that early application of circulatory support and appropriate selection of the mode of support and devices used are important for successful circulatory support.