Nocturnal worsening of symptoms affects a large number of patients suffering from asthma. Recent studies show that airway inflammation underlies nocturnal awakenings and increased airway hyperreactivity. These studies, however, yield conflicting results concerning the pathogenesis of the disease, making it difficult to understand the mechanisms involved in sustaining nocturnal asthma. This article reviews the principal pathogenetic mechanisms of nocturnal asthma, showing that worsening of symptoms at night may be the result of a more severe disease as well as of increased inflammation at night and higher susceptibility. We also review the pharmacologic treatment of nocturnal asthma which is mainly based on antiinflammatory treatment with inhaled or oral steroids or combined therapies with theophylline and beta 2 agonists. The activity of antileukotrine compounds in asthma is also summarized.