Purity >98%. 5(Z),14(Z)-Eicosadienoic Acid is a novel ?-6 C20:2 fatty acid. The more common 11(Z),14(Z)-eicosadienoic acid competitively inhibits inosine 5'-monophosphate dehydrogenase (Ki = 3.1 μM)1 and inhibits the binding of LTB4 to its receptor on neutrophils (Ki = 3.0 μM). Also, serum levels of eicosadienoic acids negatively correlate with degree of sleep disturbance. Eicosadienoic acids are converted by desaturases, in vivo, to eicosatrienoic acids, which are potent vasodilators. The physiological effects of 5(Z),14(Z)-eicosadienoic acid are unstudied.