A multiple disk, centrifugal blood pump (MDCP) for use as a ventricular assist device or as a bridge to transplant device has previously been designed and its output characteristics have been analyzed (Miller et al. 1990, 1993). The propelling mechanism of this device consists of six multiple disks assembled in a parallel configuration. Upon rotation these disks create centrifugal and shearing forces, which work to propel the fluid. This pump operates at lower rotation rates than other rotary blood pumps. The lower rotation rates reduce the chance for hemolysis, but may promote thrombosis formation due to stagnant blood flow. Previous flow visualization studies conducted by Miller et al. (1995) analyzed the blood flow patterns within the device. Results of this study indicated a region of flow stagnation between the last solid disk and the housing. In this investigation, further studies were performed that verified this recirculation. To provide washout of this region, eight, small Lexan blades were attached to the back of the last disk. Reevaluation of the flow patterns, following the blade attachment, revealed that the addition of the blades was successful in producing washout, thus reducing the possibility of thrombosis formation.