The long-term effects of an anabolic steroid (Dianabol) on the liver of motor-active mice was investigated. The pathologic changes occurring are due to cholestasis, peliosis hepatis, and diffuse hepatitis. It was assumed that a pathogenic relationship between cholestasis, peliosis, and cirrhosis exists. Neoplasms seldom occurred, but it was suggested that anabolic steroids do not primarily induce the formation of liver tumors.