Since the discovery of kallikreins in the submandibular glands in 1963 by Werle and Roden, a great number of biologically active polypeptides has been purified from, or claimed to be present in, the submandibular of the mouse and of other species. In this review, available data on the occurrence, chemical properties, localization, hormonal control, synthesis, secretion, and possible physiologic roles of 25 biologically active factors in mouse submandibular gland are analyzed. In general, these factors are androgen dependent, but not affected by the sex genotype, and are localized in the granular convoluted tubule cells in the gland. They are secreted into the saliva, but are also found in the circulation. Their physiologic roles are largely unknown.