The 12th International Congress on the Addiction Science was held from 5 to 7 September 2018 in Razi Congress Hall, Tehran, Iran. Addiction Science 2018 included Keynote presentations, plenary lectures and workshops by eminent Clinicians and Scientists from around the world with outstanding contributed papers of both poster and oral presentations. The congress covered various topics of novel clinical procedures, basic science findings, social Impacts and legislative requirements.