While allergic bronchopulmonary aspergillosis (ABPA) is well recognized as a fungal complication of asthma, severe asthma with fungal sensitization (SAFS) is not. In ABPA the total immunoglobulin E (IgE) is usually >1,000 IU/mL, whereas in SAFS it is <1,000 IU/mL, and either skin prick tests or fungus-specific IgE tests are positive. ABPA may present with any severity of asthma, and occasionally with no asthma or cystic fibrosis, the other common underlying disease. SAFS is a problem in patients with poorly controlled asthma and occasionally presents in the intensive care unit (ICU). Production of mucous plugs and coughing paroxysms is more common in ABPA. Certain underlying genetic defects seem to underpin these remarkable phenotypic differences. From a management perspective both ABPA and SAFS respond to both high doses of corticosteroids and oral antifungal agents, with ∼60% response rate in both ABPA and SAFS with itraconazole. In 50% of patients itraconazole boosts inhaled corticosteroid exposure, sometimes leading to cushingoid features. Second-line therapy data are scant, but we have shown that 70 to 80% of patients who tolerate either voriconazole or posaconazole also respond. Other useful therapies include nebulized hypertonic saline to aid expectoration of thick sputum and long-term azithromycin for its anti-inflammatory effect on the airways. Omaluzimab is useful in some patients with SAFS and occasionally in ABPA. Complications of ABPA include bronchiectasis, typically central in distribution, and chronic pulmonary aspergillosis. Most patients with ABPA and SAFS can be stabilized for long periods with inhaled corticosteroids and itraconazole or another antifungal agent. Novel immunotherapies are on the horizon.