Since 1993 several cases of spinal ataxia occurred in adult red and/or fallow deer in four farms in Southern Bavaria. The disease based on a secondary copper deficiency due to a high level of molybden and a low level of copper content in the feed. Some of the animals suffer from a severe disturbance of motion. In most cases the animals are shot at the beginning of illness. Histologically the most important lesions are in the spinal cord consisting mainly in a bilateral symmetric degeneration of dorsolateral and ventral areas of the white matter. Degeneration is caused by lamellar disintegration of the myelin connected with deposition of fine-granulated substances detectable by electronmicroscopical investigation. In the liver and other organs we always found a hemosiderosis which is also believed to be caused by copper deficiency.