This paper presents the effects of wet/dry cycling loading on the moisture uptake behavior of a Fibre Reinforced Polymer (FRP) composite used in the civil engineering sector. FRP samples of various dimensions were cut from an 'off-the-shelf' pultruded flat sheet and conditioned in a cyclic hygrothermal environment. A series of 3 consecutive moisture absorption-desorption cycles lasting for 153 days were carried out to investigate the moisture uptake behavior of FRPs. The hygrothermal procedure consisted of immersion in 60oC distilled water until saturation and consecutively drying in a 60oC oven until equilibrium was reached. After the 1st desorption cycle, it was found that FRP samples lose a significant amount of mass due to chemical decomposition, the extent of which increases as wet/dry cyclic loading progresses. The effective mass loss leads to a subsequent significant increase in the rate of moisture uptake. Mechanical behavior of the FRPs aged at 40oC and 60oC for 224 days is examined at both 'wet' and 'dry' states to reveal the reversible and irreversible effects of moisture uptake. It was revealed that the effects of 40oC hygrothermal aging on mechanical performance are reversible when samples are dried out.