Power-Take-Off covers (PTO) for a truck were injection moulded from various grades of glass fibre reinforced polyamide 6,6. Voids were generally not visible at areas of uniform cross-section, but were primarily located at areas of diverging flow. No voids were found for unfilled polyamide 6,6, while voids of varying size were produced with the fibre filled materials. Void size was affected by the average fibre length, where a high number average fibre length led to the generation of a large void size. Increasing fibre content from 50 to 60% w/w caused a reduction in average fibre length by up to 20%, which was reflected by a 20% reduction in the average void size. An inverse relationship existed between void size and the number of voids produced. Voiding was attributed to the phenomenon of foaming (material opening out by fibre spring-up) which was accentuated with high aspect ratio fibres (1/d > 20).