An industrial melt-spinning process of tetrafluoroethvlene-hexafluoropropylene copolymer (FEP) using an extruder was studied. The novel "spinneret," having both a large-diameter spinning nozzle and a high-temperature vessel, was used to solve the problem of filament breakage an the spinning line caused by high melting viscosity of FEP. The extruder, with its long feed zone, was newly designed to function with a geared pump. The strength of fibers increased with drawing of as-spun fiber. FEP fibers up to six denier were continuously produced through long-run production. According to this new process, FEP fibers can be supplied for textile or industrial application.