It is known that in the immune formations of the digestive canal of birds, which belong to the peripheral organs of hematopoiesis and lymphopoiesis, differentiation of T- and B-lymphocytes occurs under the influence of antigens that cause the development of specific (cellular and humoral) immunity. In this regard, the purpose of this study was to identify the features of the morphology of the digestive canal organs and their immune formations in ducks of the hybrid meat breed “Mulard” aged 150 days during puberty. During histological studies, pieces from different areas (oesophagus, parts of the stomach, intestines with Peyer’s spots, Meckel’s diverticula, and caecum diverticula) were selected, labelled, and fixed in a 10% aqueous solution of neutral formalin and poured into paraffin, according to the generally accepted method. Histological preparations were used to examine the features of the microscopic structure of the digestive canal organs and their immune formations and histotopography, the types of forms of lymphoid tissue were analysed, its area was calculated. It was established that the immune formations of the digestive canal organs of ducks are represented by all levels of structural organisation of lymphoid tissue, which are not equally expressed in certain parts of them. Accumulations of immune formations in the walls of the oesophagus and stomach are located in lamina propria plate of the mucous membrane and submucosal base, and in the intestines – also in the muscle membrane. Lymphoid tissue is best developed in the oesophagal tonsil, caecum diverticula, slightly less in the Meckel diverticula and Peyer’s spots of the intestine. In the wall of the oesophagus and stomach of ducks, only minor accumulations of this tissue are observed. The results obtained on the morphofunctional state of peripheral organs of hematopoiesis and lymphopoiesis allow improving technologies for raising and exploiting birds to ensure their high viability and productivity