Asthma remains the most prevalent chronic respiratory disorder, affecting people of all ages. The relationship between respiratory virus infection and asthma has long been recognized, though remains incompletely understood. In this article, we will address key issues around this relationship. These will include the crucial role virus infection plays in early life, as a potential risk factor for the development of asthma and lung disease. We will assess the impact that virus infection has on those with established asthma as a trigger for acute disease and how this may influence asthma throughout life. Finally, we will explore the complex interaction that occurs between the airway and the immune responses that make those with asthma so susceptible to the effects of virus infection.