An 8 yr, intact male red-rumped agouti (Dasyprocta leporina) was evaluated for weight loss. Examination revealed poor body condition, hypercalcemia, elevated serum 25-hydroxyvitamin D, metastatic calcification of soft tissues, and hyperechoic kidneys. The diet, formulated for laboratory rodents, contained elevated levels of vitamin D₃. Histopathology from a female conspecific that died 5 mo prior identified dystrophic mineralization and nephrosclerosis, suggestive of a vitamin D₃ toxicity. The male agouti responded well to a dietary reduction in vitamin D₃ and calcium. Six months into therapy, progressive renal failure was identified and was further managed with enalapril, phosphorus binders, and dietary manipulation. Suspected vitamin D₃ toxicity has been reported in pacas (Cuniculus paca) and agouti and has been linked to exposure to New World primate diets. In this brief communication, an agouti developed suspected hypervitaminosis D after receiving a commercial rodent diet commonly fed to this species in captivity.