Abstract: A nylon-6 filament and a method for manufacturing the same to achieve a high degree of permeability to ultraviolet rays in fabric formed from such filament comprising the steps of adding potassium or sodium bromide to the filament to render the same more pervious to ultraviolet rays than before such treatment, spinning the filament by extrusion, treating the spun filament with a solvent which dissolves superficially the filament surface with cooling after each of the steps to prevent the generation of spherulites, the extruded filament being preferably of an oval cross-sectional shape. Further it is optional to color the filament.