This paper describes a new experimental set-up specially designed for accelerated ageing tests for Fibre-Reinforced Polymer (FRP) reinforcements. The set-up uses a combination of temperature,environmental exposure (alkaline, saline, water, and concrete), and tensile sustained loads. Two seriestests I and II of Glass Fibre-Reinforced Polymer (GFRP) bars 12.7 mm-diameter were exposed to two different environments, namely the alkaline solution and de-ionized water, respectively. Temperature varying between 45 to 63°C is used to accelerate the degradation mechanism. Also, the bars were submitted to sustained tensile loads varying from 20 to 29 % of the short-term ultimate tensile strength.Both series specimens were exposed for a 104 days (15 weeks) duration. Following the accelerated ageing tests, the GFRP specimens were removed and tested for residual tensile strength. Results of these residual tensile tests are reported in this paper and compared to the guaranteed tensile and design strengths of the GFRP bar used in this experimental investigation.