© 2016 AIP Publishing LLC.Moisture content of composite prepregs are known to significantly affect the process-induced laminate microstructure and formation of microvoids during cure. In this study, the moisture absorption of eight-ply quartz (AQ 581)/Bismaleimide (BMI) composite laminates is investigated. Four different types of composite laminates are fabricated using eight plies which were preconditioned before curing at 2%, 40%, 70% or 99% relative humidity. Two different sized samples from each laminate were immersed in distilled water at 25°C. Experimental weight gain data for each sample set are obtained by periodically weighing all samples over a period of six months. The non-Fickian absorption dynamics observed in weight gain data is modeled by the three-dimensional, anisotropic, hindered diffusion model (HDM). An increase in both maximum moisture absorption and degree of anomalous behavior is observed for the composite samples as the relative humidity of prepreg preconditioning is increased. The increase in maximum moisture absorption and the extent of non-Fickian behavior are observed to correlate well with the content of the process-induced microvoids in each laminate.