An improved antistatic fiber of polyamide, polyester, polyurea, polyurethane or polysulfonamide is prepared by uniformly dispersing an antistatic additive consisting of a chain-extended propylene oxide-ethylene oxide copolymer based on a diamine, in the fiber-forming polymer, forming the fiber by conventional methods, then applying to the fiber a coating of the antistatic additive. The improved antistatic fiber is especially useful for carpet manufacture. In carpet use, the antistatic additive included in the fiber improves with age, whereas the additive externally added is gradually abraded off in use; the net result is a relatively stable antistatic capability.