The ultrastructural features of the digestive organs (stomodeum, intestine, and proctodeum) of the nematode Heterakis dispar (Schrank, 1790), beloning to the Heterakidae, which is a widespread parasite of domestic waterfowl in Azerbaijan, were studied using light and electron microscopic methods and compared with the structure of other species of the same family. The wall of the buccal cavity and pharynx are covered by cuticle, which developed from epithelial cells. Esophagus consists of three regions: procorpus, metacorpus and basal part. The wall of the lumen consists of a basement membrane, muscle cells, and a cuticle. The same cuticle is divided into cortical, homogeneous and basal layers. Between the cuticle and muscle cells at the peaks of the lumen of the esophagus, additional structures wich has not been found so far could be observed in this nematodes. The wall of the terminal bulb consists of muscle cells, glandular cells, processes of nerve cells, and the lumen is covered with a cuticle. The intestine is formed from a thick basement membrane, a single-layered epithelium with microvilli. Five zones are found in epithelial cells: basal, reticular, plasma, fibrillar and microvilli. Microvillas are located in the apical part of the epithelial cell. Unlike other nematodes family, in addition to desmosomes that connect epithelial cells, membranes also contain smooth septate junctions. The  posterior section of the intestine of helminth ends in females with an anus, and in males with a cloaca.