The levels and sources of VOCs in the atmosphere of Bursa have been investigated by measuring C-2 - C-12 VOCs which include alkanes, alkenes, alkines, aromatics and halogenated hydrocarbons in two different campaigns. The first campaign was carried out between September 14 and November 6, 2005, and the second one between March 17 and May 10, 2006. The concentrations of 112 VOCs were detected in the collected samples. The median total concentrations of VOCs were 115 and 86 mu g m(-3) for the first and second campaigns, respectively. Alkanes (x(-) = 51.50 mu g m(-3) ) are the most abundant group in the Bursa airshed, which is followed by aromatics (x(-) = 49.38 mu g m(-3) ), alkenes (x(-) = 36.86 mu g m(-3) ) and halogenated compounds (x(-) = 13.07 mu g m(-3) ). In the present study, the VOCs showed well defined diurnal, weekday/weekend and seasonal variations. Diurnal variation of most of the measured organic compounds followed traffic rush-hours. On the other hand, some VOCs such as 1-octene, 1-nonene, 1-undecene, nnonane, n-decane, 1,2,3-trimethylbenzene, undecane and dodecane have displayed unusual profiles that do not follow the traffic pattern during the first campaign due to asphalting operations. Moreover, the average T/B ratio obtained in the first campaign was found to be significantly higher than the second one. This relatively high difference between T/B ratios is an indication of the availability of different sources rather than the traffic. Therefore, it can be suggested that there were additional VOC sources than traffic in Bursa city center. (C) 2018 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.