In reviewing recent progress concerning the motor system and drug action, the following subjects will be discussed on the basis of our data : 1) the mechanisms of action of mephenesin and baclofen, 2) baclofen and γ-aminobutyric acidB (GABAB) receptor, 3) GABA-, benzodiazepine receptors, 4) control of spinal motor system by descending noradrenergic neuron, 5) pharmacology of the muscle spindle, and 6) pharmacometrics of centrally acting muscle relaxants.