Summary A method is described for determination of lipid alpha glyceryl ethers in animal tissues. Purified tissue lipid extracts are hydrolyzed and the lipid soluble fraction of the hydrolysate is fractionated on a silicic acid column. The glyceryl ether fraction is oxidized with periodic acid and the formaldehyde formed is determined colorimetrically. The alpha glyceryl ethers are a minor component of all of the tissues examined except bone marrow. The tissues other than bone marrow range in content from 0.20 to 1.35 micromoles per gram of dry lipid-free tissue and from 0.002 to 0.010 molar ratio to lipid phosphorus.