This communication describes 2 cases of choroidal coloboma in untreated Sprague-Dawley rats. On ophthalmoscopical examination, a 4 weeks old female and 11 weeks old male rats had a focal pale area which in both cases were located inferonasal to the optic disc. These pale foci were oval and well-delineated from the surrounding fundus. Subsequent examination revealed that the foci were non-progressive or non-regressive. Histologically, the lesions were characterized by lack of choroid, atrophic and indistinct retinal pigment epithelium, lack of retinal photoreceptor and external granular layers, retinal fold, retinal herniation into the sclera, and unaffected inner retinal layers.