This paper presents an experimental investigation dealing with the quasi-static behavior of the bond between GFRP (glass fibre reinforced polymer) rebars and concrete. The pull-out set-up with eccentrically GFRP bar was adopted to measure the effect of three parameters: (1) thickness of the concrete cover, (2) diameter and surface of the bar and (3) concrete mechanical properties. GFRP unidirectional E-glass rebars were considered of two diameters (6 and 8 mm) and two external surfaces (external ribbed surface cut into the bar after curing and surface deformed and coated with coarse sand). The rebars were embedded in cubic concrete specimens with three concrete covers: 10, 15 and 20 mm. Two concrete classes were used C25/30 and C50/60. The experimental results showed similar shear strength of GFRP and steel bars of diameter 8 mm, and an increasing shear strength increasing the concrete cover.