The  21st International Conference on Alcohol, Drugs and Traffic Safety organised by the International Council on Alcohol, Drugs and Traffic Safety (ICADTS) took place with great success in Gramado, Brazil on 16-19 October 2016. This international Conference sets an excellent opportunity to meet all those involved in Road Safety Research, particularly from the fields of Drugs and Alcohol, and promotes discussion and interaction with investigators, academics and professionals working in this area.