Effects of atropine, an anti-Parkinson agent, and reserpine, a pseudo-Parkinson agent, on the intensity of shivering in cats were determined. This intensity was measured by the ratio of shivering oxygen consumption rate (VO2) to resting VO2. At a dose level (5 mg/kg I. P.) in excess of that necessary to suppress Parkinson or experimentally-induced alternating tremor, atropine sulphate had no effect on the intensity of cold-induced shivering. At a dose level of O. 5 mg/kg I. V., reserpine suppressed shivering but evoked an alternating tremor with Parkinson characteristics.