A predominantly benign medulloepithelioma of the ciliary body was diagnosed in an 8-year-old girl and resected by iridocyclectomy. It recurred twice during 30 months. Highly malignant histopathologic features developed, and the eye finally perforated and had to be enucleated. No recurrence or metastases have subsequently developed. Histologically, the tumor was a nonteratoid medulloepithelioma consisting of elements resembling embryonic retina, nonpigmented ciliary epithelium, and neuroblasts, but had also areas of obvious glial and neuronal differentiation as judged by immunohistochemistry. The neuroepithelial tumor cells were positive for neuron-specific enolase, vimentin, and often for S-100 protein. The neuroblastic cells were generally positive for neuron-specific enolase and synaptophysin, but were intermixed with glia-like tumor cells positive for vimentin, glial fibrillary acidic protein, and S-100 protein. The results suggest that even a nonteratoid medulloepithelioma may be, unlike retinoblastoma, a truly multipotential tumor.