α-Farnesene rapidly autoxidizes at 1�, the primary monomeric products being conjugated triene hydroperoxides, namely (E,E)-1,5-dimethyl-1-(4- methylpent-3-enyl)hepta-2,4,6-trienyl hydroperoxide, with some of the (E,Z) isomer, and a mixture of the erythro and threo (E,E)-4-(1- hydroperoxy-1-methylethyl)-1-methyl-1-(4-methylhexa-1,3,5- trienyl)tetramethylene peroxide. The structures of these oxidation products were deduced largely from the p.m.r. spectra of alcohols obtained after reduction of the hydroperoxide groups. The mechanism of the autoxidation is discussed.