Electron microscopy of dietary fatty liver showed deposition of many fat droplets in the cytoplasm and disorderly arrangement of intracellular organelles including the lamellar structure of the rough-surfaced endoplasmic reticulum. By treating rats for a week with myoinositol, reduction of fat droplets and return of the lamellar structure of the rough-surfaced endoplasmic reticulum to normal were evident. Histological comparison of the liver sections before and after the perfusion of isolated dietary fatty liver indicated that myoinositol added to the perfusate accelerated the removal of fats from the liver to the perfusate. This was confirmed by chemical analysis of the perfusate before and after the perfusion. With liver slices, a similar acceleration, by addition of myoinositol, in removal of fats from cells to medium, was observed.