NVAD, that was paracorporeally driven for over 400 men in Japan, is controlled by adjusting a pumping rate (PR), a percentage of systolic term (PS), a driving pressure (DP) and a driving vacuum (DV). Those control parameters is changeable under a same bypass flow rate. In this study the control parameters were evaluated on hemolysis. Two pumps set under different pumping status underwent in-vitro hemolysis tests in the same condition of 4 L/min flow rate, 10 mmHg mean preload and 100 mmHg mean afterload. One was driven in a standard pumping status that was PR of 90 bpm, PS of 30%, DP of 240 mmHg and DV of 45− mmHg. The other was driven in another status. Each mock loop was filled with 2 litter bovine blood. Averaged normalized index of hemolysis in each pumping status was shown as follows.TableTo improve homolysis and hemorrhage PR should be regulated to keep a stroke volume about 55 ml. PS should be set between 30% and 40%. It is important to fit DV to keep full-fill pumping status.