The purpose of this study was to investigate the effect of lighting conditions on the frequency and severity of road accidents at both urban and rural roads in Greece. A total of 358.485 police-recorded accidents were analysed and the proposed models were developed with the use of log-normal regression. The application of these models allowed the investigation of the influence of road lighting and other parameters such as weather conditions, accident type and vehicle type on the number of casualties and injuries. It appears that road lighting contributes to the reduction of the number of accidents and their severity and that this influence increases with the increase of the severity of the accidents. The absence of street lighting during nighttime has the highest impact on the number of fatalities and serious injuries. The results show that nighttime lighting has great potential in improving traffic safety and reducing the accident severity, especially for persons killed and seriously injured. Identification of the effect of lighting on road safety should benefit road safety policy decision makers in designing and implementing appropriate road safety measures (infrastructure improvement, safety campaigns and so on).