The aim of the present study was to investigate stress reactions, speeding, number of penalties and accident involvement among different driver groups (taxi drivers, minibus drivers, heavy vehicle drivers, and non-professional drivers). A total number of 234 male drivers participated in the study. The participants were asked to complete the Driver Stress Inventory (DSI) together with a demographic information form. Five dimensions of the DSI were measured; aggression, dislike of driving, hazard monitoring, fatigue proneness, and thrill-seeking. After controlling the effects of age and annual mileage, the results of the ANCOVAs revealed differences between different driver groups in terms of both risky driving behaviours and stress reactions in traffic. Regression analyses indicated that aggression, dislike of driving, and hazard monitoring dimensions of the DSI were related to accident involvement after controlling for the effects of age, annual mileage and driver group. Dislike of driving and thrill-seeking dimensions of the DSI were related to speeding on in-city roads. (C) 2009 Elsevier Ltd. All rights reserved.