Histological development of the digestive tract of Siberian sturgeon during early life stages (1-21 days post hatch) was studied using light microscopy. At hatching, the digestive tract is represented by a gastric cavity filled with yolk and lined by endodermal cells, and a partially differentiated hindgut ; and does not communicate with the exterior as the mouth and anus are not yet opened. During the endogenous feeding phase, yolk sac resorption, stomach differentiation into a gizzard and glandular region, and the development of the anterior, intermediate region and spiral valve of the intestine are the most conspicious elements of development. At onset of exogenous feeding (9 days post hatch), yolk sac reserves are not completely depleted from the cardiac stomach, suggesting a period of mixed nutrition. Fat is accumulated in the anterior and intermediate regions of the intestine confirming the greater resistance of larvae to long periods of starvation. At this time, the alimentary canal presents the morphological digestive features characteristic of juvenile and adult stages. The buccopharynx is lined by a pseudostratified cylindrical epithelium with teeth and numerous taste buds. The esophagus is constitued by ciliated and mucous cells which are organised in two different regions. The non-glandular stomach presents a simple columnar epithelium and a prominent tunica muscularis, while the glandular stomach epithelium consists of cuboidal cellls, with numerous simple and tubular gastric glands. The anterior and intermediate regions of the intestine are similar, lined by a columnar ciliated epithelium and can be distinguished by the major number and size of mucosal folds and level of vacuolisation of the intermediate intestine. The spiral valve is lined by a simple columnar ciliated epithelium with supranuclear vacuoles. Present results reveal that the ontogenic development of the digestive tract of Siberian sturgeon is similar in comparison with other Acipenserid species. However, there exist several differences referred to the differentiation time of some digestive structures, such as the differentiation of the pyloric and cardiac stomach, the development of gastric glands, and the acquisition of an anatomically alimentary canal similar to those of juveniles and adults, which affect first feeding time and, the rearing and husbandry of Siberian sturgeon larvae.