Three composite materials (polyoxymethylene reinforced with 20% glass fibers, polypropylene reinforced with 20% of talc, poly(butylene terephthalate) reinforced with 20% of Mg(OH)(2)) were formed by injection moulding and studied for ageing resistance (NaCI soln.) and color and gloss stability after cyclic stretching-compression. The cyclic loading and ageing resulted in increasing the hysteresis loop width. Some structural changes in composites were also obsd. by differential scanning calorimetry.