Retinoblastoma is the primary ocular malignancy affecting children under 6 years of age. The development of second malignant tumors in survivors of hereditary retinoblastoma is a well-known clinical entity and a major cause of morbidity and mortality. Rhabdomyosarcomas as second primary tumors have been only rarely described. The authors report a patient with bilateral retinoblastoma who developed a myogenic sarcoma of the orbit after 5.5 years of diagnosis. The short latency period may be explained by tumor histology with the contribution of radiotherapy and chemotherapy. The prognosis of second tumors is poor despite aggressive treatment.