Conjugated linoleic acid (CLA) is known to have several beneficial biological effects in animal models, including anticarcinogenic and antiatherosclerotic effects, antiobesity, and antioxidant activity. However, reports of its antioxidant activities have been inconsistent. In this study, we investigated the possible occurrence of π-bonding between CLA and iron. CLA methyl ester was reacted with triiron dodecacarbonyl and confirmed to form π-complexes with iron tricarbonyl. This study may suggest the possible involvement of CLA in oxidation by way of interacting with iron.