Asthma is a chronic, reversible obstructive disease that when in exacerbation can present to the emergency department in a spectrum of severity. Prompt recognition of the potentially severely ill asthmatic requires a careful history and physical exam while considering alternative diagnoses for the presenting symptoms. Early administration of salbutamol and corticosteroids is indicated in almost all patients with other medications such as ipratropium and magnesium and supportive modalities like BiPAP reserved for sicker patients. The global impact of asthma is increasing, especially amongst children. While the benign clinical presentation is most common and mortality has decreased in recent decades due to improved recognition and care, the ubiquity of the condition and frequent lack of regular outpatient management contribute to the disease claiming 250,000 lives worldwide annually. The emergency physician must be prepared to assess and appropriately manage both the young child with a mild wheeze and the adult in respiratory failure.