An experimental vaccine prepared from influenza virus strains propagated in bovine kidney cell cultures, purified by zonal centrifugation, and further treated with ether was studied in man for the incidence of clinical reactions and hemagglutination-inhibition antibody levels induced. The results were equivalent to those obtained in a simultaneous study made with a commercially licensed influenza vaccine derived from viruses propagated in the embryonated egg and also purified by zonal centrifugation, but not treated with ether. Comparison of the macromethod and the micromethod for determination of hemagglutination-inhibition antibody titers revealed that lower initial titers and lesser increments in antibody levels following vaccination were obtained by the microtechnique.