The administration of drinking-water, added with LiCl (20mg Li+/l) to rats fed on "atherogenic" diet without cholesterol (casein 20% hydrogenated coconut oil 25%, sucrose 49.1%) for 90 days, elicits an expressive diminution of haematic lipids (triglycerides, free fatty acids, total cholesterol) and hepatic cholesterol. The serum dosages of thyroid hormones T3 and T4 show that the Li+ concentration used in the experiment do not inhibit the glandular functions.