This is the first time in Burma where personnel at risk against rabies have been pre-immunized and the effectiveness of such a procedure has been studied for nearly two years. The first batch of lyophilized, Semple-type, beta propiolactone inactivated anti rabies vaccine produced by the Burma Pharmaceutical Industry (B.P.I.) was used to immunize 55 B.P.I. workers previously unexposed to rabies and with no history of rabies vaccination. Three doses of 0.25 ml of the vaccine were given intradermally at one week intervals. Booster doses were given on the 98th, 392nd and 592nd day after the first dose. Blood samples were taken and serum neutralization tests were performed at varying time intervals after basic immunization and booster doses. Satisfactory antibody responses were obtained. The course of immunological response is presented and discussed.