An osmotically driven minipump continuously delivering 19 microU of pork insulin daily (6 microliter/day) was implanted subcutaneously into the upper thigh of a rhesus monkey fetus in utero at 122 days of gestation. A female infant weighing 408 g was delivered spontaneously and prematurely at 141 days of gestation. Within 6-12 hours of birth, she was in shock with signs of hypoglycemia. A radiograph of the chest showed normal lung aeration. Her blood glucose was undetectable (less than 1 mg/dl) and plasma insulin was 130 microU/ml at 12 hours. The minipump was removed, and the monkey was treated with 50% dextrose orally (2.5 g/kg body weight). The infant recovered and had a normal rate of growth thereafter. There was no neurological impairment consistent with hypoxia or hypoglycemia. Subsequent plasma glucose and insulin levels determined at various intervals were within normal limits.