Tetanus toxoid for equines has been prepared by cultivation of C. tetani into new synthetic medium for production of high potent tetanus toxin which gave high flocculation units [90 Lf (Limit of flocculation)], and high minimum lethal dose (MLD) (600,000). Tetanus toxin was inactivated by formalin, and adsorbed on aluminum hydroxide gel as an adjuvant. It was inoculated into rabbits as a preliminary evaluation for its potency, showing the permissible units allowed to be used for vaccination of horse. The vaccine was tested in horses, which exhibited higher titer of specific antibodies persisted for 8 months post vaccination.