Residue levels of the chlorinated hydrocarbons hexachlorobenzene (HCB), polychlori‐nated biphenyls (PCBs), α‐, β‐, and γ‐hexachlorocyclohexane (HCH), oxychlordane, trans‐nonachlor, aldrin, and dieldrin in adult puffins (Fratercula arctica) from two colonies in Norway (Røst 67°30'N and Hornøy 70° 20'N) showing differences in breeding performance were compared in 1982. Furthermore, residue levels in puffin chicks from Røst in 1982, when breeding failed totally, were compared with the corresponding levels in 1983, when breeding was successful. Residue levels of chlorinated hydrocarbons were also measured in eggs from Røst 1982. An autoradiographic study of the distribution of [14C] HCB in adult puffins and chicks from Røst 1982 was included.