The nematodes of the genus Heterakis are similar in appearance and a number of morphological characteristics. Therefore, determination of nematodes creates certain difficulties. H. gallinarum helminth is one of the widespread species of the genus. In the current study, the body wall of the parasite of the H. gallinarum nematode was studied at the ultrastructural level with the help of light and electron microscopic methods, and the obtained results were compared with the structures of the covering tissue of other species of the family. It was found that the bady wall of the nematode consists of 3 layers. The cuticle of the helminth is made up of 8 layers. In both individuals of the helminth, the lateral alae consist of 3 main layers. Homogeneous and fibrillar layers are many times thicker than other parts of the helminth's body. While the shape of the cuticle of both male and female H. gallinarum nematode is smooth throughout the body, 2 different shapes have been found around the bulb. This sign is not mentioned in other species of the family. Tubular structures were found between the basal part of the cuticle and the hypodermis of the studied helminth. The nervous system of the parasite is orthogonal, and the muscular type is polymyar. The number of muscle cells in between two ridges of the helminth varies from 19 to 28, depending on the sex of the worm and the part of the body of the helminth. .