Knowledge of asthma is critical for the otolaryngologist treating allergy and atopic disease. This chapter provides background in basic pulmonology and discusses the pathophysiology of asthma. It also explores the relationship of asthma to common otolaryngologic disorders, including allergic rhinitis and chronic rhinosinusitis. It is crucial to maintain a high index of suspicion for asthma when evaluating allergic patients. When allergy testing and providing immunotherapy in clinic, it is essential to elicit asthma history and current symptomatology to avoid life-threatening reactions. Most importantly, treatment of allergic disease with immunotherapy can improve asthma symptoms, improve quality of life, and decrease need for medication.