At Sahlgren Hospital, G?teborg, hepatitis B has been a serious problem for several years among the personnel in the hemodialysis and renal transplantation wards as well as in the chemical laboratories. For this reason a randomized controlled clinical study with conventional gammaglobulin and hepatitis B immune globulin was started in May 1973. The titer of anitbodies against HBsAg by passive hemagglutination was 1:100 and approximately 1:350,000, respectively. Newly employed staff without a history of jaundice and without demonstratable HBsAg (RIA) or HBsAb (RIP) in serum were enrolled in the trial. Assignment of the two preparations was performed by random numbers and the ampoules were labelled only with the serial number of the participant. Three cc of either preparation was administered i.m. within seven days after admission and was repeated three months later. After that no further injections were given. Each participating employee was followed up with liver function tests, IEOP, RIA and RIP tests for at least six months after the last injection. Preliminary results from this double-blind study, which is still going on, are presented.