Abstract: An arrangement for stretching thermoplastic fibers of synthetic polymers, particularly polypropylene, polyester or polyamide, for producing high strength yarns,comprises a delivery mechanism for delivering fibers, a stretching mechanism for stretching fibers, and a plurality of heated rollers arranged between the delivery mechanism and the stretching mechanism for deviating the fibers and means for applying to the fibers a force which is opposite to a direction of movement of the fibers, none of the rollers being driven and at least one of said rollers is provided with a brake, the fibers passing around the rollers without slippage.