Effects of alchohol and fat content in a balanced diet on chemical composition and morphology of liver were investigated in growing rats. Fourth eight male rats of Sprague-Dawley strain weighing about 160g were divided into 4 groups ; high fat diet group, alcohol-administered high fat diet group, low fat diet group and alcohol-administered high fat diet group, low fat diet group and alcohol-administered low fat diet group. High and low fat diets supplied 30% and 12%, respectively, of total calorie intake from fat, and alcohol was given by adding ethanol in drinking waster at 10%. Diets contained adequate amounts of all nutrients required for rats, including lipotrpoic agents(choline and methionine) to minimize effects of factors other than alcohol on liver damage. Ratios of liver weight to body weight were statistically different among groups. Liver/dody weight ratios alcohol-administered rats were significantly higher than those of non-alcohol groups after 6 weeks treatment. Although total lipid and triglyceride per gram liver were increased in alcohol-administered rats, especially low fat diet fed rats, the values were not significantly different. Opticmicroscopical observation revealed increase in cell size and no change in morphology of liver. Examination of hepatocytes by electron microscopy showed that fat droplets were observed in all groups but enlarged in the alcohol-administered low fat diet fed rat. Contents of protein, cholesterol and phospholipid were not affected by alcohol consumption. The level of lipid peroxide was significantly lower in the livers of alcohol-administered rats than in the livers of non-alcohol groups. The results of this study indicate that even moderate alcohol drinking and dietary fat content did not affect any significant change in composition and morphology of liver until 6 week treatment but that even moderate alcohol drinking caused some signs of steatosis of liver.