It is the biggest nematode in birds, with females measuring 72 to 112 mm long. The body is semi transpicuous, creamy-white and cylindrical. The anterior end is characterized by a prominent mouth, which is surrounded by three large tri-lobed lips. The edges of the lips bear teeth-like denticles. The body is entirely covered with a thick proteinaceous structure called cuticle. The cuticle is striated crosswise throughout the length of the body and cuticular alae are poorly expressed. Two conspicuous papillae are situated on the dorsal lip and one on each of the subventral lips. These papillae are the sensory organs f the nematode. A. galli is diecious with distinct sexual dimorphism. Females are considerably longer and more robust, with vulva opening at the middle portion (approximately midway from anterior and posterior ends) of the body and anus at the posterior end of the body. The tail end of females is characteristically blunt and straight. Males are relatively shorter and smaller (measuring 50 to 76 mm long), with a distinct pointed and curved tail. There are also 10 pairs of caudal papillae towards the tail region of the body, and they are arranged linearly in well-defined groups such as precloacal (3 pairs), cloacal (1 pair), post-cloacal (1 pair) and subterminal (3 pairs) papillae. Eggs found in the feces of transited birds are oval with smooth shells and measure 73-92 by 45-57 microns
