In the right eye of an 11-year-old girl, a large iridociliochoroidal mass developed that measured approximately 14 x 12 x 9 mm in size. The tumor initially resembled a uveal melanoma on the basis of clinical appearance and ancillary studies. Enucleation was not done, however, because of the patient's age and the unusual transillumination properties of the lesion. Instead the tumor was resected by a partial lamellar iridocyclochoroidectomy with an excellent visual outcome. Light and electron microscopy and immunohistochemistry established that the tumor was a leiomyoma. A literature review showed that all but one of the 15 previously reported cases of ciliary body leiomyoma that the authors were able to verify were found in women with an average age of 30 years. The possible significance of this apparent age and sex predilection for this unusual tumor is discussed, and the clinical features which may help differentiate leiomyoma from uveal melanoma are presented.