A sorbent obtained by treatment of cyanogen bromide-activated Sepharose 4B with mono-N-DNP-hexamethylenediamine has been shown to be effective in the affinity chromatography of pepsin, pepsinogen and acid proteinase from Aspergillus awamori. It is considered that 2,4-dinitrophenyl residues of the sorbent interact specifically with the hydrophobic zone of the enzyme, which may belong to the substrate binding site. The chromatography of chymotrypsin on the same sorbent supports this assumption.