Metabolic and hematological changes produced by immobilization were studied in monkeys ( Macaca mulatta) with temporal lobe and spinal cord lesions. The normal hyperglycemic response to immobilization was abolished by bilateral destruction of the hippocampus, hippocampal gyrus and amygdala, and by transection of the spinal cord above the splanchnic nerves, but remained intact after less extensive lesions of the temporal lobes or after sections of the cord sparing one or both lateral columns. No changes were induced by immobilization on the sodium, potassium and cholesterol levels of the plasma. The normal granulocytosis produced by immobilization was significantly decreased following complete transection of the cord at low thoracic levels and greatly reduced after high thoracic transections; it was unchanged after incomplete sections sparing one or both ventral columns or after extensive bilateral ablations of the temporal lobes. The lymphopenia of immobilization was of the same degree after bitemporal ablations and low spinal transections; following high thoracic transections the lymphopenic, and eosinopenic, responses were completely abolished for a period of seven to ten days, following which they were gradually restored. It is concluded that the limbic lobe structures studied are essential to the hyperglycemic response to immobilization and that this response is mediated through the lateral columns of the cord while the granulocytosis of immobilization is not affected by similar limbic lobe lesions and is mediated through the ventral columns of the cord.