It is well recognized that the safety of biological products prepared from blood, such as ProfilateR, a freeze-dried factor VIII concentrate, may be increased by testing for hepatitis B surface antigen.Abbott Laboratories has been routinely screening all plasma donations for hepatitis B surface antigen since January, 1971. Originally, the screening was performed using the second generation counter-immunoelectrophoresis technique, AUS-tect. In April, 1973, the counter-immunoelectrophoresis testing was replaced with the more sensitive third generation radioimmunoassay technique, Aus-RIA, for routine hepatitis B surface antigen testing. The most sensitive current radioimmunoassay technique, Aus-RIA II, has been used since February, 1975. This presentation will review the results of six years of testing experience. The data indicate that the incidence of positive donors in the commercial plasmapheresis system is 1.4 per 1,000, similar to that reported for a volunteer blood program.