The current study was conducted to evaluate the effects of conjugated linoleic acid (CLA) on the expression of involved genes in insulin resistance, at the presence of induced TNF-? stress. To aim this, C2C12 murine myoblast cell line were used. The experimental treatments consisted of :A) the concentrations of 25, 50, 100, 150, 200 and 400 µM CLA per each ml of culture medium, B) the concentrations of 10, 15 and 20 ng/ml of TNF-? in the culture medium C) the concentrations of 50 and 100 µM of CLA with 10, 15 and 20 ng/ml of TNF-? concurrently. Our results indicated that the concentrations of 50, 100 and 150 µM of CLA at 24, 48 and 72 h increasd the survival of cell (P 0/05). After treatmant compared with that in the control group. Concentrations of 10, 15 and 20 ng/ml of TNF-? at 24 h decreased cell survival (P 0/05) compared with the control group. The effect of treating CLA and TNF-? simultaneously showed that the amount of cell death caused by TNF-? is inhibited by the concentrations of 50 and 100 µM CLA (P 0/05). CLA effects of mentioned CLA concentrations on Fndc5 gene expression at 48 increased the expression of these genes (P 0/05). CLA concentration of 50 µM and 100 µM at 24 and 48 h after treatment increased PGC-1? gene expression (P 0/05). Concentration of 10 ng/ml TNF-? 24 hours after treatment increase Fndc5 expression (P 0/05). The simultaneous effect of CLA at concentrations of 50 and 100 µM, as well as 15 and 20 ng/ml TNF-? increase Fndc5 expressio while the concentration of 50 µM of CLA with 10 ng/ml of TNF-? showed no remarkable difference as compared to the control group ( P 0/05). Therefor, the findings of the present in vitro study indicated that using CLA may improve insulin resistance induced by TNF-?, markedly. Keywords : Conjugated linoleic acid (CLA), tumor necrosis factor alpha (TNF-?), insulin resistance, Fndc5 genes, PGC-1? gene.