The relatively low modulus of elasticity and the different surface treatment of fibre reinforced polymer (FRP) rebars have a direct impact on the spacing of cracks and the profile of bond stress between cracks. Hence, a tension stiffening model for FRP rebars is likely to be very different from that of steel rebars. In this paper, tension stiffening behaviour is investigated through the test results of six reinforced concrete (RC) beams with glass FRP (GFRP) reinforcement covering a wide range of reinforcement ratios. It is found that the stabilized cracking phase is reasonably characterized by an average effective modulus of elasticity. Tension stiffening for GFRP is much lower than for steel rebars. A tension stiffening model is proposed for an RC tie with the particular GFRP rebars used.