Acute, severe asthma attacks can be precipitated by a variety of stimuli including exposure to aeroallergens, viral respiratory infections, pollutants, and occupational chemicals. Alternaria is a major aeroallergen in many parts of the world. Sensitivity to Alternaria has been increasingly recognized as a risk factor for the development and persistence of asthma, asthma severity, and potentially fatal asthma exacerbations. We present the case of a patient with IgE-mediated sensitivity to Alternaria who developed an acute, life-threatening asthma attack during the peak Alternaria season. We describe the aerobiology, pathophysiobiology, diagnosis, and treatment options for patients with Alternaria-induced asthma.