We report the synthesis and fatigue characterization of fib erglass/epoxy composites with various weight fraction of graphene platelets infiltrated into the epoxy resin as well as directly spray-coated on to the glass micriofibers. Remarkably only-0.2% (with respect to the epoxy resin weight and-0.02% with respect to the entire laminateweight)of graphene additives enhanced the fatigue life of the composite in the flexural bending mode by up to 1200fold. By contrast, under uniaxialtensile fatigue conditions, the graphene fillers resultd in 3-5fold increase in fatige life. The fatigue life increas (in the flexural bending mode)with graphene additives was-1-2 orders of magnitude superior to those obtained using carbon nanotubes. In situ ultrasound analysis of the nanocomposite during the cyclic fatigue test suggests that the graphene net work toughens the fiberglass/epoxy matrix interface and prevents the delamination/buckling of the glass microfibers under compressive stress. Such fatigue resistant hierarchical materials show potential to improve the safety, reliability, and cost effectiveness of fiber reinforced composites that are increasingly the material of choice in the aerospace, automotive, marine, sports, biomedical, and wind energy industries.