A 14-yr-old Argentine horned frog (Ceratophrys ornata) presented for evaluation of a chronic, cutaneous mass. A white, semifirm raised mass was present in the skin on the right cranial dorsum. Excisional biopsy was performed. Fine-needle aspiration cytology and histopathology were consistent with an iridophoroma, a type of chromatophoroma. Recurrence occurred and removal was repeated 4 months and again 2 yr following the initial surgery. The original mass did not have definitive criteria of malignancy but did extend to surgical margins, which may account for repeated local recurrence. Although chromatophoromas are relatively common cutaneous neoplasms in reptiles and amphibians, iridophoromas are rarely reported in amphibians. This is the first report of an iridophoroma in an Argentine horned frog.