Crude tetanus toxin and toxoid were prepared by methanol precipitation. The toxin was purified by a combination of TEAE�cellulose and Sephadex G�200 chromatography at pH values less than 6� o. The toxoid was purified by DEAE� cellulose at approximately neutral pH values. The nature and amount of amino acids of the culture medium which had condensed with the tetanus toxoid proteins during detoxification with formaldehyde was determined.