Erysipelothrix rhusiopathiae was isolated in large numbers from the kidneys and was visualized histologically in the kidneys, heart muscle, skeletal muscle, selected lymph nodes, and the submandibular salivary glands of a black and red tamarin (Saguinus nigricollis) following an acute fatal illness. Sites (heart valves, joints) usually associated with disease mediated by E rhusiopathiae appeared uninvolved.