Choroidal osteoma is a benign, ossifying tumor, first described by Gass and Williams in 1978, typically found in healthy young females. Usually it is localized in the posterior pole of the eye, near the optic disc and the macula. Its aetiology is unknown: it may be caused by osseous metaplasia of the retinal pigment epithelium, or it may represent a kind of choristoma. The diagnosis of the choroidal osteoma is based mainly on its very characteristic clinical picture, ultrasonography and computed tomography--both demonstrating calcific plaque corresponding to the lesion. The most important complications of the tumor are: subretinal neovascularisation, subretinal and intraretinal haemorrhages, serous and haemorrhagic retinal detachments. Neovascularisation can be successfully treated by laser photocoagulation, which can even lead to decalcification and involution of the tumor. Choroidal osteoma must be differentiated mainly from amelanotic choroidal melanoma, choroidal nevus, choroidal haemangioma, choroidal metastasis, granuloma, organized subretinal haemorrhage, sclerochoroidal calcification and age-related macular degeneration. In this paper we present a case of a choroidal osteoma recognized in an 11-year-old girl. There have been no signs of tumor's growth or signs of subretinal neovascularisation for three years of follow-up. As far as we know, it is the first case of this disease described in Polish literature.