Objective: The objective of this research was to study the histological structures of proventriculus by light and scanning electron microscope and to investigate the localization of glucagon immunoreactive cells within the turkey proventriculus. Materials and methods: Ten adult healthy turkeys were used in this study. The specimens were fixed in 10% buffered neutral formalin. The tissue samples were studied through routine histological and immunohistochemical techniques. Other samples were used for scanning microscope. Results: This study confirmed that the turkey proventriculus was formed from four tunics; tunica mucosa, tunica submucosa, tunica muscularis and tunica serosa. The lamina epithelialis was simple columnar and gave positive reaction in Periodic Acid Schiff (PAS) stain. The lamina propria contained simple tubular glands lined with columnar cells with lymphocyte infiltration. The submucosa contained proventricular glands formed with many round lobules. Each lobule was consisted of secretory tubules radiating from the central lumen of the lobule. The lining epithelium of the central lumen was columnar epithelium. The epithelium of the secretory tubules was cuboidal. Scanning electron microscopic observations showed the mucous membrane was consisted of many macroscopic papillae that formed from many folds which separated by furrows. Immunohistochemical observations revealed that glucagon immunoreactive cells were mainly determined inside the proventricular glands than within the surface epithelium mainly in the basal portion of the lobules and in the epithelium of central lumen of gland lobules. Conclusion: The structure of proventriculus structure in turkey has some variations as compared to other species of birds, and this may be attributed to the diet and its nutritious behavior. [J Adv Vet Anim Res 2018; 5(3.000): 290-298]