Ageing is characterized by sarcopenia partially explained by a decreased sensitivity of protein metabolism to anabolic stimuli such as insulin or amino acids (leucine). Animals fed a n-3PUFA-enriched-diet have shown an increased of whole body protein metabolism sensitivity to insulin in bovine (Gingras et al.2007) associated with an increased of signalling pathways linked to protein metabolism (i.e mTOR). Smith et al, 2011 have confirmed that n-3PUFA also improved mTOR signalling pathways in elderly muscle. However, in this former study, the effect on insulin relatively to amino acid sensitivity remains unknown since the improvement of muscle protein synthesis was shown under a hyper-aminoacidemic-hyperinsulinic clamp. The present work aimed at demonstrating if protein metabolism sensitivity to insulin alone and/or amino acids (leucine) alone was improved in old rat muscle with a chronic n-3PUFA supplementation. 30 rats (16 month-old) were submitted to a control diet or a n-3PUFA enriched diet for 4 months. The response of muscle protein synthesis and proteolysis to insulin (0,1,5,75nM) or to leucine (0,100,200 m M) was measured in vitro on epitrochlearis muscles. Our results showed that protein synthesis stimulation or proteolysis inhibi- tion by leucine was not changed when animals were dietary supplemented