Light microscopic and transmission and scanning electron microscopic observations were performed on the aortas of two 4- and 6-year-old deer affected with cervine ataxia and two 6-month- and 4-year-old healthy deer. Examination of the aortas from affected deer by transmission electron microscopy revealed the absence of distinct elastic laminae in the internal elastic lamina and tunica media, but discontinuous and irregular clumps of elastin were present. Scanning electron microscopy disclosed immature architecture of elastic fibers in the aortas from the copper-deficient deer, and the architecture was similar to that of a 6-month-old healthy deer.