Branched hydrocarbons from the unsaponifiable lipid fraction of the Biceps femoris muscle of Iberian pigs were analyzed. Fifty-five Iberian pigs were distributed to seven groups according to management system (short Montanera and long Montanera, i.e. fed on acorn and pasture for 55 and 75 days prior to slaughter, respectively, and Pienso, fed on a concentrate diet), and genetic type. A branched hydrocarbon, neophytadiene, was identified only in samples from the pigs fed on the extensive system, with higher levels being found in pigs from the long Montanera group, than in those from the short Montanera group; this compound was not found in the Pienso group. Genotype did not affect the level of branched hydrocarbons found.