The effects of glass fibres and annealing on the microstructures and spherulitic morphology of a glass fibre-reinforced nylon 6,6 were investigated. The annealing effects on matrix crystallinity of nylon 6,6 composites with varying glass fibre contents were measured and the morphology of the composites were examined using both the microtomed bulk samples and thin composite films prepared by melt crystallization. It was found that fibre breakage during injection moulding was significant for composites with glass content higher than 20 wt %, and the spherulite size as well as the crystallinity were reduced by the additions of glass fibres. Upon annealing, the start of a log time rate increase of matrix crystallinity was delayed by the addition of glass fibres. Glass fibre-induced transcrystallinity was not observed in injection-moulded composites; however, columnar spherulites were found to develop along the glass fibres in melt-crystallized thin composite films. Differences in morphological observations between the two sample preparation methods are also discussed.