Total alkaline protease activity, 2 different trypsin-like proteases and cathepsin B activity were separately analyzed in the submandibular glands of the rat. One of the trypsinlike enzymes was found to be testosterone induced and responsible for the increased alkaline proteolytic activity in the salivary gland extracts of the adult male rats. The enzyme has recently been described in detail: its pH optimum is pH 8.2, lima bean inhibits its activity completely and Trasylol and CuCl2 very effectively. The trivial name glandulain is used for the enzyme. Androgen dependency was demonstrated in a series of prepuberal rats, where the sexual development was followed by estimating the relative volume of the steroid-producing cells in the testis or the appearance of corpora lutea in the ovary. In the male submandibular glands the glandulain activity was significantly higher than in the female glands from the 40th day of life onward, which was about 10 days later than the first signs of increased activity of testicular Leydig cells. Castration of male animals decreased the glandulain activity to 1/5 of the normal value, but it did not reach the normal female low level during the 4 months’ follow-up period. Testosterone was able to bring the enzymic activity back to the normal level. Testosterone doubled the activity in the female glands in both intact and castrated animals. (Endodrinology83: 1224, 1968)