This document is the ninth in a series of Tobacco Knowledge Summaries and is prepared with the objective to summarize the current evidence on the association between tobacco use and asthma. This is also intended as an advocacy tool to widely include health care professionals, in particular pulmonologists and respirologists, in the fight for tobacco control and prevention of tobacco related adverse health effects. This knowledge summary was prepared by World Health Organization in collaboration with the Forum of International Respiratory Societies, the Global Initiative for Asthma and The University of Tasmania.