Abstract: Fine expanded PTFE fiber with round cross section and smooth outer surface are obtained by twisting flat stretched filaments above the optimum limit for these fibers and subsequently further stretching with heat treatment. These filaments can be used for fabrics, among other applications, and they present the following properties: low shrinkage, low elongation under tension and high tensile strength. The invention also suggest a process of manufacturing said fiber, comprising the steps of twisting said expanded PTFE filament in excess to the optimum for the fiber, and stretching the twisted fiber under heat treatment until the fiber returns to its optimum twist and is fixed.