A study was performed to examine the ability of dietary oleic anilide to alter 12-hydroxyeicosatetraenoic acid (12-HETE) production. The structure of oleic anilide, synthesized by reacting oleic acid with aniline, was confirmed by mass spectrometry. The purity of oleic anilide, 75%, was measured by gas chromatography. Oleic acid, which constituted the remaining 25%, is a major component of the rapeseed oil vehicle. Balb/c mice were fed oleic anilide as 0.75% of their diet by weight for three weeks. Their lungs were excised and examined for 12-HETE production in vitro. The 12-HETE levels were significantly (p < 0.01) lower in mice fed oleic anilide than in mice fed the oleic acid control diet. This result illustrates eicosanoid production as a target of fatty acid anilide toxicity. The fatty acid composition, including arachidonic acid, of mouse lungs from both dietary groups was not different. This confirms the availability of substrate for 12-lipoxygenase in both groups. Spleen weights were higher in mice fed oleic anilide than in control mice (p < 0.005). These observations are relevant to immunoregulation and the autoimmune syndromes noted in patients of the Toxic Oil Syndrome (TOS).