Abstract | Ascaridia species were the most common nematodes infecting pigeon. They included Ascaridia galli and Ascaridia columbae. The infected birds suffered from different clinical signs which varied from weight depression, retarded growth, decrease in egg production, gastrointestinal disturbance and intestinal blockage to high mortality rates, according to the severity of infections, therefore this study was aimed to determine their infection rates, the morphological differences by light and scanning electron microscopes (SEM), induced histopathological lesions in different visceral organs and the effect of green onion on A.galli cuticle in vivo. Our study reported 25% and 10% infection rate for A.galli and A. columbae, respectively. Microscopical examination revealed that the ultra structures of A. columbae resembled that of A. galli except for lip carrying two triangular teeth on its inner surface instead of two tooth-like projections in A. galli and absence of subannuli and cuticular vesicles instead of their presence in A. galli. In addition,the male caudal end carried ten and thirteen pairsof caudal papillae in A.galli and A.columbae, respectively. Exposure to green onion showed wrinkled cuticular surface in lips, loss some of labial amphids and the appearance of granulation tissue in the oral cavity of A. galli by SEM and showed cuticular damage by histopathological examination. Also,histopathology revealed hemorrhage, congested blood vessels, fatty degeneration, necrosis and leukocytic infiltrationin the examined liver, lungs, heart, intestine, brain and ovaries. Finally, our study recommends using finely chopped green onion as a food additive in case of infections with Ascaridia species because they had a significant anthelmintic effect on the cuticle and sensory papillae of A. galli.