A concentrate of tryptic enzymes was obtained by ultrafiltration of fish sauce made from cod viscera. The recovery of enzyme activity during ultrafiltration was good (> 80%) showing that polysulphone membranes can be applied successfully in ultrafiltration even at very high salt concentrations (20-25%). The concentrate could be stored for 8 months at 3-degrees-C or spraydried with only minor activity loss. Preliminary results indicate that the enzyme preparations can be applied for maturation of herring fillets. A normal fish sauce fermentation was achieved after readdition of the ultrafiltration permeate to the fish-sauce fermentation tank.