Clinical presentation, treatment, and outcome of trilateral retinoblastoma. In this report, three new cases of trilateral retinoblastoma are presented. The clinical presentation, treatment, and outcome of the patients are described and compared with those of 32 cases that have been previously reported in the literature. A positive family history was obtained in 68% of the patients. The mean age at diagnosis of bilateral retinoblastoma was 7.2 months. The mean age at diagnosis of trilateral disease was 39.7 months, resulting in a mean latent interval of 32.6 months. The mean time from diagnosis of trilateral retinoblastoma to death was 6.6 months, and all patients died with spinal metastases. The patients who received no therapy survived an average of 1.3 months after the diagnosis of trilateral disease. The patients who received any form of definitive therapy survived 9.7 months. Five patients who had complete or dramatic response to therapy by computed tomography scans had local intracranial tumor present at autopsy. Therefore, more aggressive local therapy may be warranted. 