Patients with the inherited, bilateral form of retinoblastoma have an increased incidence of osteogenic sarcoma such that the mortality from the secondary tumor exceeds that of the initial bilateral retinoblastoma. We report a 29-year-old male survivor of bilateral retinoblastomas originally diagnosed at 8 months of age, whose treatment eventually included bilateral enucleation, bilateral orbital radiation, and systemic chemotherapy. At age 26, a tumor removed from his right maxillary sinus was diagnosed as fibroma. At age 29, he developed an inferior orbital mass that extended into the right maxillary sinus. A biopsy and comparison with the previous maxillary sinus mass revealed both lesions to be leiomyosarcoma. Both light and electron microscopy supported the diagnosis. The patient has survived treatment with orbital exenteration and maxillectomy combined with postoperative radiation to the right orbital-maxillary area. This appears to be the fourth case of leiomyosarcoma in the third decade of life in a male patient with a previously irradiated orbit after enucleation for bilateral retinoblastoma. Leiomyosarcoma appears to be another orbital tumor associated with bilateral retinoblastoma.