A 28-month-old white male, 7 months status postenucleation for retinoblastoma, presented with lethargy, irritability, anemia, and thrombocytopenia. Bone marrow examination revealed almost total replacement of marrow elements with clumps of small round basophilic cells. Electron microscopic study of the marrow revealed clumps of cohesive tumor cells with intermediate junctions, establishing a diagnosis of metastatic retinoblastoma.