Radiochemically labelled (3‐14C)‐decoquinate (ethyl 6‐n‐decyloxy‐7‐ethoxy‐4‐hydroxyquinoline‐3‐carboxylate) has been synthesised and used to measure residues remaining in liver, kidney, teg muscle, breast muscle, blood, heart, fat and skin after administration to broiler chickens at a dose equivalent to 0.008% decoquinate in the feed. Residues reached their maximum levels three days after dosing began and they remained substantially constant thereafter. These levels were less than 1.0 ppm in all the tissues examined. After withdrawal of medication, residue levels fell rapidly in most tissues (<0.1 ppm after 89 h) with the exception of fat and skin.