Rolling Mouse Nagoya (RMN), weaver and reeler mice were examined for the clinical effectiveness of drugs (thyrotropin releasing hormone (TRH), reserpine, L-dopa) that are reported to facilitate or alter the metabolic system of noradrenaline (NA). Behavioral changes and ataxic gait were recorded by 16mm cinefilms and EMG of the thigh extensor muscles. In addition, latencies in the reflex discharge of the muscle by tilting load were measured before and after the intraperiotoneal injection of each drug and compared to those of normal littermates. TRH injection increased spontaneous behavioral activity in RMN and weaver, and shortened the latency of the reflex discharge by tilting load in RMN. Reserpine injection did not increase behavioral activity, but was accompanied by a slight shortening of latencies in the reflex discharge by tilting load only in RMN. L-dopa did not affect behavioral and EMG activities of these cerebellar mutant mice. No remarkable deficit has yet been in any selective intracortical neurons in RMN and no other characteristic abnormality in central and peripheral nervous, skeleton and muscular systems. It was, therefore, suspected that there was a possibility of metabolic disorders of NA in the cerebellum not only in RMN, but also in patients with certain spinocerebellar degenerations.