To investigate whether free fatty acid impair insulin signaling proteins to inhibit insulin action in rat islet cells.After rat islet cells were incubated with palmitate (0.25 mmol/L) or oleate (0.125 mmol/L) for 12 hours, 24 hours and 36 hours, western bolt was used to assess the protein abundance of cPKCalpha, Grb2 and FERK2.The protein content of cPKCalpha were significantly upregulated and the protein abundance of Grb2 and ERK2 was decreased comparing with control in rat islet cells after incubated with free fatty acids.Free fatty acids may inhibit insulin activity in rat islet cells through up-regulating the expression of cPKCalpha or down-regulating the expression of Grb2 and ERK2.