This 3-hydroxyhexanoic acid methyl ester is a high purity standard that is ideal for analysis and biological systems. Polyhydroxyalkenoates, polyesters produced by bacteria fermentation, are used for carbon and energy storage and are of interest in studies regarding their synthesis, properties and mechanisms. Short chain-length polyhydroxyalkenoate monomers such as 3-hydroxyhexanoic acid may have pharmaceutical properties. The biologically natural chiral (R)-3-hydroxyhexcanoic acid is an intermediate in fatty acid biosynthesis. 3-hydroxyhexanoic acid has been found in patients with ketoacidosis.1 3- hydroxy fatty acids are used as biomarkers for fatty acid oxidative disorders of both the long- and short-chain 3-hydroxyacyl- CoA dehydrogenases.2,3