Hybrid composites of low density polyethylene (LDPE) reinforced with intimately mixed short sisal and glass fibers were prepared by solution mixing technique. The mechanical properties of these composites have been investigated with reference to the effects of orientation and composition of fibers in them. It has been observed that the composites containing longitudinally oriented fibers exhibit better mechanical properties than those with randomly oriented ones. Also it is seen that the mechanical properties increase with increase in the volume fraction of glass fibers in the hybrid composites. The effect of chemical modification of sisal fibers on the properties of 50:50 sisal/glass fiber composites has also been studied. The hybrid effect was calculated by the additive rule of hybrid mixtures using the mechanical properties of individual composites. A positive hybrid effect was exhibited by the composites for all the mechanical properties except for elongation at break.