The present study was carried out on 430 domestic pigeons (318 nestlings and 112 adults) from January to December 2020 in Sadat City, Egypt to determine the prevalence of Trichomonas gallinae and their histopathological effects. Pigeons were clinically examined for trichomoniasis. Birds with oral lesions of T. gallinae were subjected to wet mount preparations and Giemsa stained smears from their mouth, esophagus, and crops.  Histopathological examination of infected tissues was performed. The results observed revealed that the prevalence rate of T. gallinae was 4.2 % (18/430). The infection rate was higher in nestlings (4.4%) than in adults (3.6%). The highest infection rate was recorded during summer (5.8%) while the lowest rate was recorded in winter season (1.9%). Moreover, morphological descriptions of recovered T. gallinae organisms were reported. Microscopically, the oral caseous masses revealed plasma cell and lymphocyte infiltration linked to several multinucleated foreign body giant cells and several round to oval pale eosinophilic structures with basophilic properties nuclei which represent Trichomonas gallinae parasites.