There is an increasing concern about the possible adverse effects of diesel exhaust particulates on human health. In a diesel exposed occupational group composed of 120 toll collectors, a cross-sectional study was performed to evaluate the chest radiographs and 40 toll collectors were selected for computed tomography examination according to hyperinflation and linear markings. The wall thicknesses and luminal diameters of trachea, main bronchi, and segmental bronchi of right apical and posterior basal segments were measured with manual tracing method. The walls of right upper bronchus in exsmoker toll collectors were significantly thicker than those of nonsmokers (p=0.011). A positive correlation was observed between age and the right upper bronchus wall thickness (r=0.577, p=0.000). An inverse correlation was found between the working duration and the diameter of right main bronchus (r=-0.366, p=0.020). A positive correlation was seen between smoking and the right upper bronchus wall thickness (r=0.457, p=0.005). Diesel exposure might have a role in increase of thickness of large airways wall and a decrease in the diameters of large airways. Studies in this area are needed to protect the population under the diesel exposure risk.