An adult male channel-billed toucan (Ramphastos vitellinus) was presented with a history of weakness, dyspnea, and severe dilatation of the coelomic cavity, which was caused by accumulation of serohemorrhagic fluid. Radiographs revealed increased radiodensity and thickness of the descending aorta and a pectoral mass, and blood test results revealed anemia, hypocalcemia, hypoproteinemia, and hyperuricemia. On ultrasound examination, a hyperechoic enlarged soft tissue mass was found in the caudodorsal region of the coelom. The bird did not respond to supportive care and died. Postmortem examination revealed severe, bilateral nephromegaly due to multifocal to coalescing renal tubular adenomas (adenomatosis), which was complicated with renal gout and soft tissue mineralization. Relevant concurrent diseases included hepatic hemochromatosis, subcutaneous cestodiasis with cellulitis, and systemic amyloidosis. There are few documented cases of neoplasms in ramphastid birds and to our knowledge, this is the first report of a renal neoplasm in a channel-billed toucan.