The polytetrafluoroethylene-filled (PTFE) poly(m-phenylene isophalamide) (PMIA) composite blocks are prepared by compression molding. The friction and wear of PTFE-filled PMIA are investigated on a block-on-ring machine by running the PMIA composite block against plain carbon steel (AISI 1045 steel ring). The worn surface of PMIA composite and the steel counterface are examined by using electron probe microanalysis (EPMA). It is found that PTFE-filled PMIA exhibited considerably lower friction coefficient and wear rate than pure PMIA, Furthermore, the lowest wear rate is obtained when the composite contains 20 vol % PTFE. EPMA investigations show that there are some debris that could restrain the wear of the PMIA composites oriented along the sliding track and embedded in the surface of PMIA composite. A kind of stripe transfer film that contains abundant F element should be the main reason for the improvement of the tribological properties of PTFE-filled PMIA composites.