Although it has long been recognized that the common cold is a potent trigger for symptoms of asthma, the mechanisms underlying the association between upper respiratory infection and increased lower airway obstruction remain obscure. The use of experimental infection of volunteers with or without respiratory allergies has enabled direct comparisons of common cold symptoms in these two groups. Furthermore, techniques such as bronchoalveolar lavage and segmental antigen challenge have been used to directly sample lower airway fluids and tissues during acute viral infection. This review summarizes the findings of studies examining the separate and combined effects of rhinovirus infection and allergen exposure on airway physiology and inflammation.