Glucose uptake, lactate formation and glycogen synthesis by isolated rat hemidiaphragm were measured in the presence and absence of diethyl ether and insulin. Ether caused a significant decrease in glucose uptake by isolated skeletal muscle. The increase in glucose uptake which was induced by insulin was not blocked by ether. Ether caused a significant increase in the rate of lactate formation by isolated skeletal muscle, and added insulin doubled this effect of ether. Ether induced glycogenolysis in the isolated rat hemidiaphragm and also altered the disposition of the increased glucose uptake by the tissue which occurred in the presence of insulin.