The paper refers to threat assessment of dangerous goods (DG) in transportation of the European Union and the Republic of Poland. Dangerous goods in the European Union are carried by inland waterways, rail and road. In Poland 87.5% of DG have been carried by road and 12.5% by rail in 2014. DG can cause an accident and lead to fires, explosions and chemical poisoning or burning with considerable harm to people and the environment. There is not monitoring system in Poland to control in real time road transportation of dangerous goods. Proposition of National System of Monitoring Dangerous Goods in Poland was presented. Realization of mentioned kind of system may significantly contribute to improving safety of people and environment.