Heptadecanoic acid, or margaric acid, is a saturated fatty acid. Its molecular formula is CH₃(CH₂)₁₅COOH. It occurs as a trace component of the fat and milkfat of ruminants, but it does not occur in any natural animal or vegetable fat at high concentrations. Salts and esters of heptadecanoic acid are called heptadecanoates.