1 Intravenous injection of rabbits with the polyamines spermine (10-30 mg/kg) and spermidine (50-90 mg/kg) produced hyperglycaemia.2 Given by intraventricular injection, spermine and spermidine gave rise to hyperglycaemia in doses 250-500 times smaller than those effective intravenously.3 Intraventricular injections of the polyamines also produced hyperglycaemia in rats. Adrenal demedullation abolished the response.4 In the rabbit, the hyperglycaemia resulting from intraventricular injection of polyamines was abolished in reserpine-treated animals. Anaesthesia had no effect on the response unless accompanied by anoxia, when the response was potentiated.5 Intracisternal injections of the polyamines in rabbits were less effective than intraventricular injections in that doses about four times larger were required to elicit an equivalent response.