p-Chlorobenzoic acid is a major metabolite of analgesic agent zomepirac sodium in rat (present as conjugates) and mouse and a minor one in monkey and man. It is a metabolite of antidepressant Lofepramine hydrochloride, and anxiolytic and a muscle relaxant Chlormezanone too. Sodium salt of p-Chlorobenzoic acid is used as a preservative. p-Chlorobenzoic acid may prove useful clinically to prevent and reverse the accumulation of toxic levels of acyl- and arylCoA esters. If the hepatic damage in Reye’s Syndrome is due to the dead-end formation of the CoA esters of acyl- and aryl-CoA esters, then p-chlorobenzoic acid may block their formation, thereby relieving the inhibitions of gluconeogenesis and urea synthesis and preventing some of the damage to the liver.