Ambient concentrations of C2-C12 volatile organic compounds (VOCs) were measured at Bursa, which is the fourth largest city of Turkey. Two measurement campaigns were carried out between September 14 to November 6, 2005 and March 17 to May 10, 2006. Fifty one VOCs were regularly determined in each chromatogram. However, only BTX compounds are discussed in this study. Concentrations of BTX compounds showed well-defined diurnal cycles. Concentrations increased starting at 06: 00 am in the morning, reaching to a maximum somewhere between 9: 00 to 11: 00 am. Then concentration decreased, until the evening rush hour, owing to increasing mixing height during day time. Then concentrations of BTX increased in the afternoon rush hour which extended to 08: 00 pm. BTX concentrations remained low throughout the night. High binary correlations between BTX compounds suggest a common source, which are traffic emissions. However, other non-traffic sources were also found to be effective, for benzene in the November to March campaign.