Experiments were performed on spinal cats. The author studied the effect of sodium amytal, evipan, pentothal, ether, chloralose, ethyl alcohol, chloral hydrate and of urethane on the monosynaptic (tendon-elbow extensor and knee) reflexes of the cervical and lumbar sections of the spinal cord. Sodium amytal, evipan, pentothal and ether inhibit mainly the knee jerk while chloral hydrate and urethane, the elbow extensor reflex. In the doses employed chloralose did not materially change any of the reflexes, while ethyl alcohol either inhibited both reflexes to the same degree, or had a greater inhibitory effect on the knee jerk. Changes in the tendon reflexes under the effect of narcotics were not directly influenced by the higher divisions of the central nervous system, interaction of different areas of the spinal cord, reciprocal relationships, blood pressure variations, the site of administration of the above preparations or by the different degree of vascularization of the cervical and lumbar sections of the spinal cord, but depend on the, as yet uninvestigated, peculiarities in the pattern of the above-mentioned reflexes.