The lipicl profile of connective tissue, isolated from the rat and the rabbit, by the sponge-implantation technique, is presented. This tissue is rich in cholesterol, phospholipid, and neutral fat. Several sex, age, and species differences in the concentration of its lipids are reported. Simultaneous determination of serum lipids indicates that there is no significant correlation between the lipid values of the serum and connective tissue. The relationship of these findings in connective tissue, the chief constituent of the intima, to the problem of atherosclerosis is discussed.