in this investigation, the effect of glass fiber and talc loading on the mechanical and physical properties of chopped glass fiber reinforced polybutylene terephthalate composites has been studied. further areas of investigation include the effect of fiber length, talc particle size and talc surface treatment. the so-called radlite process is employed on a laboratory scale to prepare composite sheets. since the sheets show a preferred fiber orientation, testing was carried out in two directions, parallel and transverse to the direction of preferred fiber orientation (mfd and tfd). the fiber loading clearly dominates the composite performance and has a pronounced positive effect on it. increasing the talc loading reduces strength. under certain conditions, talc can be as efficient as glass fibers in increasing the composite modulus higher talc loadings do not impair the composite impact properties a reduction in fiber length from 12.7 to 6.4 mm causes improved properties in the mfd, which may be explained by a higher degree of fibre orientation. no significant effect of the talc particle size can be established as a result of measuring the variable over too narrow a range. a talc surface treatment does not result in improved composite performance