Ocular tumors are rarely seen in farm animals. Iridociliary epithelial tumors are the second most common tumor of the eye in dogs and cats, but there is just one report of this tumor in sheep. This case report described the history, clinical signs, histopathological and immunohistochemical findings, and surgical management of an iridociliary adenoma tumor in a 3-year-old Iranian Shaal sheep with signs of anorexia, depression, loss of vision, and a mass covering the left eye. The mass had protruded from the left eye globe but had not penetrated the periocular tissues. Enucleation was performed to excise the tumor. Periodic acid-Schiff (PAS) and Alcian blue staining methods were done for the mass, but the result for both of them was negative. Slides were also immunostained for antibodies against cytokeratin AE1/AE3, vimentin, and S-100 protein. The results were positive for vimentin but negative for cytokeratin and S-100. According to the results of histopathology and immunohistochemistry, the type of tumor was diagnosed as iridociliary adenoma. To our knowledge, it was the second report of the iridociliary tumor in the sheep and the first report of this tumor in the Iranian Shaal breed.