1) The effect of glucocorticoid on 1-(14)C-acetate incorporation into major lipids classes and each fatty acid. Male ICR mice were injected intramuscularly Dexamethasone 1.33mg/kg for five days in one group, for ten days in the other and not injected as a control. One hour after injecting ten microcuries of 1-(14)C-Acetate intraperitoneally, (14)C was recovered in the whole blood and liver of the both groups, and activities were increased in whole blood and decreased in liver of the ten-day group. (14)C was recovered mainly in the triglyceride and phospholipid among major lipid classes of peripheral blood and liver, and there was a negative correlation of radioactivities of triglyceride and phospholipid between the liver and whole blood during the treatment with steroid. Radioactivity recovered in the oleic acid was decreased in percentages among total fatty acids and esterified fatty acids of phospholipid and of triglyceride. Therefore, it is considered that mono-unsaturation mechanism in fatty acid might be supppresed by steroid treatment, whereas a relative increase of recovery of (14)C was observed in fatty acids with lorger chain than linoleic-acids chain. 2) Effect of GCH on conversion of 1-(14)C-linoleate and 1-(14)C-linolenate in the total fatty acids of the liver to other several fatty acids with long chain. Ten microcurie each of 1-(14)C-linoleate and 1-(14)C-linolenate were mixed with human serum, albumin, agitated at 55℃ for 30 minutes and injected intraperitoneally into the three groups mentioned above. One hour later the animals were killed and their livers were excised for assessment. A few conversions of 1-(14)C-linoleate into longer and shorter chains of fatty acids were observed in the both groups treated with steroid, but 1-(14)C-linolenate was converted significantly and highly to other longer chain of fatty acids, especially in the five-day group. 3) The effect of anabolic steroid hormon on lipids metabolism in liver and whole blood. Oxandrolone 4mg/kg body weight was given orally to the two groups treated with steroid, and non-treated group with oxandrolone and steroid was kept as control. Loss of body weight and elevation of serum lipids appeared to be less than in the group treated with only GCH. Concerning the study on main lipid fractions of liver, when Dexamethasone was injected together with Oxandrolone, percentage of incorporation of 1-(14)C-acetate into triglyceride was reduced, whereas that into phospholipids was increased.