Nomex fabrics have been irradiated in a xenon-arc Weather-Ometer, and the resulting changes in combustion char acteristics, tensile properties, and degree of discoloration were measured. The ignition and hurning proprties of ir radiated and unirradiated specimens were determined with the TRI Flammahility Analyzer employing burning con figurations of 45° and the horizontal (12 o'clock). Indications are that the limiting oxygen index is reduced and the burning rate increased as irradiation time is increased. Flammability results obtained with DOC FF 3-71 were not conclusive. Nevertheless, the reduction in flame resistance of Nomex as a result of irradiation appears to be less of a potential problem than the concomitant decrease in tenacity.