The pro-apoptotic ability of conjugated linoleic acid (CLA) has been partly accounted for its anticarcinogenic effect although the precise mechanism of action remains elusive. In this study we characterized the biochemical events governing CLA-mediated apoptosis in Jurkat T cells. CLA induced a time-and dose-dependent activation of caspase-3. Pre-treatment with antioxidant molecules (trolox and quercetin), antioxidant enzymes (catalase and superoxide dismutase) metal chelator (EDTA), reducing agent (N-acetyl-L-cysteine), NADPH oxidase or protein kinase C (PKC) inhibitor (diphenyleneiodinium and Gö 6976, respectively) suppressed CLA-mediated caspase-3 activation. Moreover, CLA treatment increased the NADPH oxidase activity and depleted the intracellular pool of reduced glutathione. These results suggested that CLA can trigger apoptosis through an oxidative stress mediated by the PKC/NADPH oxidase pathway. The proposed mechanism provides a new insight into the anticancer activity of CLA.