Hemoptysis is the expectoration of blood from the lower respiratory tract, usually from bronchial arteries. The most common causes are acute respiratory infections, cancer, bronchiectasis, and chronic obstructive pulmonary disease. No cause is identified in 20% to 50% of cases. Hemoptysis must be differentiated from pseudohemoptysis, which is blood that originates from nasopharyngeal or gastrointestinal sources. The initial evaluation includes determining the severity of bleeding and stability of the patient and may require bronchoscopy for airway protection. Mild hemoptysis comprises more than 90% of cases and has a good prognosis, whereas massive hemoptysis has a high mortality rate. A history and physical examination can assist in identifying an etiology, but diagnostic testing is often required. Chest radiography is a good initial test, but it has limited sensitivity for determining the site and etiology of the bleeding. Computed tomography and computed tomography angiography of the chest with intravenous contrast are the preferred modalities to determine the etiology of bleeding; however, bronchoscopy may also be needed. In addition to supportive medical treatment, management should include treatment of the underlying etiology because recurrence often takes place in the absence of treatment of the identified cause. Bronchial arterial embolization is used to treat massive hemoptysis, particularly when an involved artery is noted on computed tomography angiography. Surgery is reserved for patients whose medical treatment and embolization are not effective.