An unusual large tan iris mass in a 19-month-old child was removed by iridocyclectomy and studied by light microscopy, immunohistochemistry, and flow cytometry. The excised mass consisted of granulomatous inflammation with numerous osteoclast-like giant cells and scattered atypical Touton giant cells. Immunohistochemistry studies showed that the cells were most consistent with mononuclear histiocytes. Flow cytometry showed that 90% of the cells sampled were T-lymphocytes, with a predominance of T-suppresser cytotoxic cells. Juvenile xanthogranuloma (XG) of the iris can occur as a large solitary mass, without signs of intraocular inflammation or hyphema.