BACKGROUND & AIMS: Peripheral arterial disease (PAD) is strongly associated with endothelial dysfunction and inflammation, which portend a high cardiovascular risk. Accordingly, we investigated the effects of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on endothelial function and inflammatory status in affected individuals. METHODS: PAD patients were randomly divided into two groups. In Group I (n=16) pre-enrollment therapy was not modified, while in Group II (n=16) n-3 PUFAs 1g b.i.d. for 3 months were added to the previous treatment. Endothelial function was assessed by measuring plasma soluble thrombomodulin (sTM) and brachial artery flow-mediated dilation (FMD), and the inflammatory status by measuring high-sensitivity C-reactive protein and myeloperoxidase. RESULTS: In Group II, n-3 PUFAs reduced sTM levels from the median value of 33.0ng/mL (interquartile range 16.7, 37.2) to 17.0ng/mL (11.2, 33.7) (p=0.04), and improved FMD from 6.7% (3.7, 8.7) to 10.0% (6.2, 14.2) (p=0.02). Conversely, these markers did not change in Group I. After 3 months, the levels of inflammatory markers remained unmodified in both groups. CONCLUSIONS: In PAD, n-3 PUFAs induced a marked improvement in endothelial function. Conversely, they did not affect the inflammatory status. In future, large, prospective studies are needed to investigate whether n-3 PUFAs, by improving endothelial function, would reduce the incidence of ischemic events in a population at high risk.