Publications and our own results of researches into the role of enzymes exo- and endosecreted by digestive glands, acting as regulators of their secretion and motor activity of gastroduodenal complex were summarized. Exosecreted to its cavity enzymes adapt an enzymatic spectrum of secretes to the composition and properties of duodenal content through M-cholinergic, peptidergic, and beta-adrenoceptive mechanisms on the basis of reception of the complex properties: enzyme-substrate-product. We described the effect of enzymes on the glands producing them, and the influence on secretion of the other digestive glands, regulatory effects of peptide fragments of proteolytic enzymes, and their zymogenic precursors. The digestive glands enzymes endosecreted and circulated in blood produce a hindrancing and inducing effect on these glands, take part in supporting of homeostasis of organism. Mechanisms of influence of enzymes and their fragments on the activity of digestive glands were analysed.