A new method of factor VIII purification has been devised which involves chromatographic separation on aminohexyl-substituted agarose. Relatively large volumes of starting material can be processed compared to the volume of agarose employed and satisfactory yields are obtained. Factor-VIII-clotting activity is separated from the other related substances and resultant products appear to be stable. While separation of clotting activity occurs with relative ease, the antigen and ristocetin co-factor are hardly segregated, if at all. This provides a little more information about the interrelation of these substances. Results suggest that ion-exchange is involved in the mechanism of separation but additional hydrophobic or steric effects cannot be ruled out.