Rabbits were treated with dextrose, amantadine hydrochloride, or 6-mercaptopurine and simultaneously injected with Influenza A2/Jap/305/57 and bovine serum albumin. Amantadine administered by different routes and in several doses had no effect on the rate or titer of antibody synthesis of these two antigens. A definite immunosuppressive effect was observed in rabbits treated with 6-MP, but this effect was only observed in anti-BSA synthesis. No effect was observed using influenza virus as antigen.