Reaction of the methyl ester of ustilic acid A (15,16-dihydroxypalmitic acid) with a methyl Grignard, oxidation of the glycol grouping, bromination, and hydrogenolysis produced 15-methylhexadecanoic acid. A series of 15-keto acids resulted from reaction of the amide of ustilic acid A with the appropriate Grignard reagent followed by oxidation of the glycol grouping. Infrared absorption characteristics of these compounds are described.