A process for the continuous heat-setting and shrinking of synthetic fibers in the form of yarns with a given twist and/or in the form of tows with a forced crimp by means of a heated fluid medium with temperatures between 100.degree. and 220.degree.C, characterized in that the fibers are treated in a two-step continuous process, first at temperatures below 100.degree.C in water or saturated steam temperatures, or slightly superheated steam, respectively, and subsequently with air, superheated steam or a superheated steam-air mixture at high temperature conditions between 150.degree. and 220.degree. C.