Despite the significant progress in dealing with fatal accidents in the European Union over the last years, serious non-fatal accidents remain a major health problem. In 2016, the European Commission published for the first time data on the number of serious injuries, using a common definition for all Member States. The purpose of this study is to investigate the factors affecting the number of serious injuries in road accidents in Europe. Generalized Linear Models were developed, correlating the number of serious injuries in road accidents and the severity of accidents with transport and economic factors. The increased rates of passenger cars with EuroNCAP safety rating equal to five stars and the use of buses lead to the reduction in the frequency of serious injuries and the severity of road accidents. The existence of older vehicle fleets and the increased use of motorcycles have the opposite effect on the examined indicators.