© APFIS 2019. All right reserved. Reinforcing concrete members with Fibre-Reinforced Polymer (FRP) bars has been the focus of several recent research studies. Yet, only a small number of these research studies investigated the behaviour of FRP bar reinforced concrete columns. This study presents a comprehensive experimental comparison between the structural behaviour of circular normal strength concrete (NSC) and high strength concrete (HSC) specimens reinforced longitudinally with Glass Fibre-Reinforced Polymer (GFRP) bars and transversely confined with GFRP helices. The test parameters were: 1) concrete strength; 2) type of the reinforcement (steel or GFRP); 3) pitch of the transverse GFRP helices and 4) loading condition. The results revealed that the contribution of the GFRP bars was about half of the contribution of the steel bars in the total load carrying capacity of both NSC and HSC specimens. It was also observed that the confinement efficiency of the GFRP helices was better than the confinement efficiency of the steel helices. However, the confinement efficiency of the GFRP helices decreased with the increase in the concrete strength or increase in the eccentricity of the applied axial load.