Brachymystax lenok is an important commercial fish that are now at risk of extinction due to over exploitation and environmental pollution in China. The development of culture techniques for supplementation would benefit from a better understanding of the endocrine cells in digestive tract and their role in ingestion, digestion, and absorption of food. We documented the localization, regional distribution, and relative frequency of endocrine cells in the digestive tract of B. lenok. We used 6 mammalian antisera, including 5-hydroxytrptamine(5-HT), somatostatin(SS), pancreatic polypeptide(PP), gastrin (GAS) and substance P(SP) to locate the endocrine cells in 1-, 2-, and 3-year-old individuals by immunohistochemical SABC. 5-HT immunoreactive(-ir), SS-ir, and PP-ir cells were detected in the esophagus and throughout the stomach, including the stomachus cardiacus, stomachus fundus, and stomachus pyloricus of all age classes (except the esophagus of one-year old fish). The highest density of 5-HT-ir and SS-ir cells was in stomachus fundus of three-year old B. lenok(P<0.05). The density of PP-ir cells was significantly higher in the stomachus pyloricus of 2-year-old individuals than in 1- and 3-year-old fish (P<0.05). However, these three kinds of endocrine cells were not detected in the foregut, midgut, hindgut, or rectum. GAS-ir cells, GLU-ir cells, and SP-ir cells were not detected in any part of the digestive tract of 1–3-year-old B. lenok. As the endocrine cells of other teleosts, the 5-HT-ir , SS-ir, and PP-ir cells of B. lenok were divided into two types: open type with cytoplasmic process and closed type without a cytoplasmic process. In summary, 5-HT-ir, SS-ir, and PP-ir cells mature in the gastrointestinal tract of B. lenok after 1 year, and have the same regulatory function at this time as in adults. The density of these cell increased with age.