Since March 1973, approval procedure for hemodialysis systems devices is mandatory in France. Basically it controls the minimum requirements to insure the effective, safe performance of these devices in the treatment of end stage renal disease. They include dialysing fluid systems, monitoring equipment and dialyzers. We have controlled 28 dialysate delivery system monitors and 21 dialyzer models. During the approval procedure a high rate of cases which do not meet the minimal requirements, were observed: 61 p. cent for the identification of the device, 72 p. cent for the safe electrical current limits (French National Standard), 83 p. cent for the monitoring and 22 p. cent for the duration (1,000 hours for center utilisation, 1,500 hours for home utilisation). Better results were found with dialyzer performances. Ultrafiltration flow rate and solute dialysance measured in vitro under clinical conditions of flow rates and pressures correlated well with the values claimed by the manufacturers. Problems encountered during the approval procedure stemmed from the lack of National and International Standard for hemodialysis systems and the poor compliance of the manufacturers to "good manufacturing practice" rules.