Compounds containing a carboxylic acid group may be metabolized along several routes. However, the most common pathways involve conjugation reactions with amino acids or glucuronic acid. Also, chain shortening due to beta-oxidation occurs when the carboxylic acid group is attached to a suitable aliphatic moiety. The various metabolic reactions of compounds containing the carboxylic acid group were reviewed by Caldwell. I Additional reactions of the carboxy group have been discovered which reveal that numerous I ipophilic conjugates may be formed. This subject was reviewed by CaldweW3 and Quistad and Hutson4 and the findings demonstrate that the acids may undergo chain extension or incorporation into triglycerides, cholesterol esters, and fatty acid derivatives. In addition to these reactions which occur in the tissues, the metabolism (e.g., decarboxylation or reduction) of some carboxylic acids may be carried out by the intestinal microflora.