The effects of chronic insulin administration on the metabolism of isolated rat adipose cells have been studied. The results suggest that chronic hyperinsulinemia increases insulin binding and the capacity of rat adipose cells to transport and metabolize glucose without changing the cells' sensitivity to insulin. The mechanism of increased insulin-stimulated glucose transport in adipocytes from chronically hyperinsulinemic rats has also been examined. These results suggest that chronic hyperinsulinemia in the rat enhances insulin's stimulatory action on glucose transport in adipocytes by increasing the intracellular pool of glucose transporters through a generalized effect on the net synthesis of intracellular protein.