The long-term durability of Glass Fiber-Reinforced Polymer (GFRP) bars in concrete need to be investigated and analyzed. This paper presents an experimental investigation into comparison of the durability of the bond between GFRP and steel reinforcing bars in concrete under different environment. For all bars, five environmental conditioning media were used. The bond strength after exposure was considered as a measure of durability of the bond between the bars and concrete. Ninety pullout specimens were used to study the effect of different environment on bond strength of GFRP and steel bars to concrete. Experimental results showed no indication of any bond degradation due to the continuous immersion in tap water, alkaline and salt solutions for ninety days. To the contrary the bond strength values of the conditioned specimens were comparable or slightly higher than the bond of the controlled specimens. The acid+chloride solutions have more detrimental effect on bond strength of GFRP bars in concrete. GFRP and steel bars have similar bond strength retention under alkaline environment. And the rate of bond degradation is very slow due to concrete reinforcement.