An esteroprotease hydrolyzing p-tosyl-L-arginine methyl ester (TAME) has been purified to homogeneity from male mice submandibular glands by the ammonium sulphate precipitation, Sephadex gel chromatography and DEAE-cellulose chromatography. The enzyme was shown as a single chain acidic protein (pI = 5.7) with the molecular weight of 27.5 K and evidence was obtained to reveal that it was similar to protease A. Using this enzyme as antigen we prepared anti-TAMEase antibody. The immunoblotting studies on tissue specificity using 20 different tissues from male mice revealed that cross-reactivities with anti-TAMEase antibody were observed in the crude extract from the sublingual gland, parotid gland and pancreas. The species specificity studies with the submandibular glands of 7 different species indicated that only the crude extract from rat submandibular glands reacted against anti-TAMEase antibody but it exerted a low TAMEase activity.