Fibre-reinforced polymer (FRP) composite reinforcement is now commonly used as internal reinforcing bars for concrete structures subjected to aggressive environments where corrosion of steel reinforcement is likely. However, the FRP bar surface resin has been shown to deteriorate when exposed to aggressive environments and this can result in a significant loss of bond strength with the surrounding concrete. In this paper, a review of FRP bar pull-out tests is collated for the following hygrothermal conditions; full immersion in water, full immersion in alkaline solution, full immersion or wet-dry cycles in sea water solution, full immersion in acidic solution and freeze/thaw cycles in water or chemical solution. The durability of the bond behaviour is analysed in terms of influence of material properties, specimen geometry, an simulated environmental condition. The analysis has highlighted the large scatter that exists for experimental results between studies and seeks to explain this scatter through discussion of the impact of exposure to material properties and the importance of sound experimental design. Key knowledge gaps are identified that can be used to inform future studies.