The clinical application of cardiac prostheses requires a pump that has the highest reliability and no defects. Considering the possibility of clinical implantation in the future, quality control and inspection systems have been incorporated into the fabrication process of biolised cardiac prostheses. Inspection procedures are employed at every strategic point in the pump fabrication process, including visual inspection, dimensional check, material test, performance test and s.e.m. observation. Over the past one-and-a-half years we have inspected 480 components and assemblies from 49 total artificial hearts and left-ventricular assist devices. A total of 93 defects and failures were detected by the inspection system, of which 48 defects were repaired in the fabrication lines. The remaining components were rejected and removed from the pump fabrication lines. The quality of trileaflet dura mater valves was significantly improved by the incorporation of the quality-control system. Since most of the fabrication and assembly are performed manually at the present time, the quality control has contributed greatly to improved device reliability.