Hemagglutinin of rabies virus was prepared from CVS 11 strain grown in suspension culture of baby hamster kidney-21 cells maintained in a medium containing 0.4% bovine albumin and no serum. Optimal conditions for demonstration of rabies hemagglutinin included low temperature, pH 6.2, and the use of goose erythrocytes. Normal human, burro, and goat sera contained high titered nonspecific HA inhibitors which were difficult to remove. Specificity of rabies HA antigen was, however, demonstrated with antirabies hyperimmune sera which were treated with a modified kaolin adsorption technique. The same methods were used with minor modifications in the preparation of hemagglutinins of vesicular stomatitis virus (VSV)-Indiana, VSV-New Jersey, Cocal, and Kern Canyon viruses.