Two enzymes possessing collagenolytic activity were isolated from the hepatopancreas of crab Paralithodes camtschatica by ammonium sulfate fractionation and DEAE-Sepharose chromatography. It was shown that the specific activities of proteases A and C toward insoluble collagen were equal to 400 and 300 Mandl units/mg protein, respectively. The mol. wt of homogenous proteases A and C determined by gradient polyacrylamide gel electrophoresis in the presence of SDS and 2-mercaptoethanol were equal to 30 and 24 kDa, respectively. The isoelectric point values for the enzymes were determined as 2.5 and 2.9. Both enzymes lack carbohydrates. The amino acid compositions of two crab proteases were measured. The optimal conditions for the enzyme catalysis and the catalytic constants for collagenolytic proteases A and C with respect to Bz-Arg-pNA and Bz-Tyr-OEt have been determined. Inhibition data led to classification of the purified enzymes as serine proteases.