The use of Glass Fibre Reinforced Plastic (GFRP) rebars as a potential replacement for steel reinforcement has raised quite a bit of controversy among the professionals and engineers engaged in the construction industry. Divergent views have been opined by the professionals for its usage in civil engineering structures. Even though, the GFRP rebar has some advantages with regard to corrosion, its usage in the construction industry is still a big question mark due to its low modulus of elasticity and serviceability aspects towards construction of structural elements. In this background, experimental investigations have been taken up at the CSIR—Structural Engineering Research Centre, Chennai to study the static and fatigue behavior of concrete beams reinforced with GFRP and Thermo Mechanically Treated (TMT) bars. Concrete beams with GFRP bars of dimensions 100 mm × 200 mm × 1500 mm have been subjected to static monotonic loading to study the flexural behaviour and companion concrete beams of same dimensions with TMT bars have also been investigated. The investigations have revealed that the concrete beams with GFRP bars resulted in unacceptable deflections and crack widths, with regard to serviceability, compared to the companion beams with TMT bars of same amount of area of reinforcement. The fatigue studies conducted on concrete beams, at four different load ranges, with GFRP bars were also not encouraging. This paper presents the details of experimental investigations and the results.