This study was aimed at determining volatile organic compounds concentrations in indoor and outdoor sites located in Rome characterized by different traffic intensity. Indoor and outdoor air passive samplings were effected in private locations during four seasonal periods. In all sites about 50 pollutants were determined qualitatively and benzene, toluene, ethylbenzene and xylenes were determined quantitatively. The analytical results generally showed a dependence of indoor and outdoor pollutant concentrations on traffic density and a seasonal variability. Moreover, many sites were characterized by the presence of toluene and xylenes indoor concentrations higher than outdoors indicating indoor sources.