Shivering and heat loss in the cold were determined in 46 cats several weeks or months after bilateral destruction of various septal and hypothalamic regions. Septal lesions had no effect on either parameter. The tremor was abolished or markedly reduced in cats with lesions in the dorsomedial region of the posterior hypothalamus, but postural, pilomotor and behavioral responses to cooling persisted. Lesions of the dorsolateral region of the posterior hypothalamus increased heat loss despite the presence of shivering, huddling and piloerection. These results confirmed our previous electrical stimulation data that the primary region controlling the efferent (motor) aspect of shivering is the dorsomedial region of the posterior hypothalamus and additionally indirectly suggested that the dorsolateral region of the posterior hypothalamus is implicated in cold-induced cutaneous vasoconstriction.