Ageing of adhesive-bonded aluminium-diglycidyl ether of bisphenol A based aliphatic amine-cured acrylic modified epoxy resin reinforced with fused silica exposed to 100% humidity and cycled between 42-48-42 degrees C every hour is reported. Moisture uptake was followed using broadband dielectric measurements. It was found that the adhesive absorbs moisture very rapidly, the adhesive undergoes significant swelling, and there is a consequent reduction in strength consistent with plasticization of the matrix. The dielectric measurements parallel closely the changes occurring in the adhesive bond line and provide a nondestructive method for monitoring the changes in bond strength. The changes that occur are dominated by the effects of moisture on the adhesive, various pretreatments have little effect on the ageing process, and interfacial failure in this case does not make a significant contribution to the failure of these joints.