Samples of Fiber B and PRD 49 which were the forerunners of current Kevlar aramid fibers were subject to a limited number of tensile tests and tensile fatigue tests in order to determine their fracture morphology. The fibers were examined by optical and scanning electron microscopy. Both tensile and fatigue failure occurs by axial splitting, with the fatigue splits being much longer. Compressive effects in snap-back cause kink bands to form. The fatigue strength is only marginally less than the tensile strength.