During the measurement campaign performed in August/September 2005 non-methane volatile organic compounds (NMVOCs) were studied at different locations in the city of Wroclaw, Poland. The measurements covered NMVOCs in the range of C-1 to Cu-10. Samples were collected using Carbotrap and Carbosieve SIII solid adsorption tubes and analysed off-line by thermal desorption and GC-FID analysis. Measurements were performed on purpose to assess the contribution of different emission categories to the observed NMVOC porfile by using chemical mass balance modelling (CMB). Profiles of NMVOCs for traffic emissions were measured in a downtown intersection and during driving through the city. Solvent emission profiles for industrial sources were measured in the vicinity of different factories in Wroclaw. To obtain the ambient NMVOC concentrations sampling was performed at different points located in Wroclaw. The sampling sites represented residential, industrial, mixed settings and an area down-wind from the city centre. The results of the present work show that traffic emissions rather than other sources determine the ambient NMVOC composition in the city. Traffic exhaust contributes approximately 99% to the NMVOC concentration in the city centre of Wroclaw and down-wind from the city. A significant influence of investigated industrial solvent emissions could only be observed in the close vicinity of the factories, where the contributions of solvent emissions were up to 90%.