A severe case of polycystic nephropathy was seen in an adult European roe deer (Capreolus capreolus), culled in a German hunting district. The doe had bilaterally drastically enlarged kidneys, completely riddled with variably sized, fluid-filled cysts of up to 4 cm in diameter. Histopathologic and ultrastructural examination revealed disseminated formation of cysts with flattened epithelial cell linings in the entire renal parenchyma, as well as severe dilations of renal tubules, marked interstitial fibrosis, nephron atrophy, and chronic interstitial lymphoplasmacytic infiltrations in the intercystic kidney tissue. These morphologic findings most likely resemble the hallmarks of autosomal dominant polycystic disease in humans, and present the first detailed description of a case of polycystic kidney disease in a roe deer.