Process and composition relating to novel, fine denier, homogeneous, curly synthetic fibers are set out. The process comprises orientation of a fiber-forming, slowly crystallizing, synthetic polymer composition in fiber form, generally after melt spinning, such orientation resulting from application of a longitudinal tensile force to said fiber above the crystallization temperature range and maintaining it at least through such range during a controlled, substantially axially symmetric cooling of the fiber. The novel fibers have a substantially axially symmetric, residual tensile force differential between their outer sheaths and inner portions, are generally of helical configuration and can exhibit more than about fifteen turns per linear centimeter.