Pheochromocytomas, rare in all species except rats, dogs and cattle, are neuroendocrine tumours of adrenal chromaffin cells. This case reports the occurrence of a tan-coloured mass in medulla of the left adrenal gland in a 6 - year - old female sheep dead from pneumonia. Histopathologically, the tumour was composed by pleomorphic cells with marked nuclei and abundant eosinophil cytoplasm. Immunohistochemistry evidenced expression of neuron specific enolase (NSE) and S100 protein in neoplastic cells associated with a strong Ki-67 activity. This tumour was diagnosed as pheochromocytoma. This is the first report of a pheochromocytoma in a sheep.