The study aimed to find out the histomorphological and histochemical structures of the walls of the stomach parts in mallard. To conduct this investigation, twelve healthy birds were collected from local suppliers at Baghdad province. Later on, birds were subdivided into three equal subdivisions, each of four for gross, histological and histochemical approaches. All birds were anesthetized and their abdomens were dissected, then their stomach were identified and photographed in situ. Organs were grossly described and specimens were immersed either in 10% neutral buffered formalin or in Bouin's solution for histological fixation and then processed for histological and histochemical staining techniques, which were comprised Hematoxylin-eosin, Masson Trichrome, Periodic Acid Schiff (PAS) and PAS-Alcian Blue (AB) (pH 2.5). The gross findings showed that the stomach was consisted of two distinguishable chambers, that were proventriculus and ventriculus. The proventriculus was tubular-shaped organ. The ventriculus appeared fusiform in shape and covered by thin fatty tissue. There was well demarcation between proventriculus and ventriculus. Histologically, the proventriculus mucosa lining was simple columnar epithelium. The submucosal consists of numerous and voluminous deep submucosal glands. The covering of the ventriculus was simple cuboidal. Presence of thick cuticle layer with well-developed muscular stomach. Muscularis mucosa appeared characteristically thick layer of smooth muscle bundles arranged as, inner circular and outer longitudinal layers. The tunica muscularis appeared, as a very thick structure of smooth muscles fibers. Three layers of muscles were distinguished that were thin inner, outer longitudinal and very thick intermediate circular layers.

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