Glass fibre-reinforced polymer (GFRP) bars are used as internal reinforcement in several structural applications, while research is currently developing in this field. Although the use of GFRP rebars in bridge applications is increasing, more experimental data needs to be collected on the behaviour of GFRP bars under fatigue loading. This paper presents and discusses the results of 9 ribbed GFRP bars tested under low-cyclic tension-tension fatigue under different stress levels. A detailed comparison is made between the available experimental fatigue data tested under high frequencies and low-cyclic fatigue tested in this study. The main advantages and disadvantages of this type of test are discussed.