Pulmonary edema of water immersion, which is not associated with aspiration or a closed glottis, is infrequently described in the literature. Swimming-induced pulmonary edema is a syndrome whose pathophysiologic characteristics have not been fully elucidated. Immersion alone has marked effects on central vascular volume, redistribution of pulmonary blood flow, and lung volumes. These changes are more prominent in cold water. These changes, coupled with an elevated cardiac output, may expose regions of the capillary bed to high pressures that favor the extravasation of fluid by hydrostatic forces and potential stress failure of the capillaries. Patients with swimming-induced pulmonary edema present with dyspnea, cough, hypoxemia, and occasionally hemoptysis. Physical examination and chest radiographs usually reveal evidence of pulmonary edema. Treatment is symptomatic and conservative. Improvement and resolution of symptoms are usually rapid, with radiographic normalization in 24 to 48 hours. We describe here 3 cases of swimming-induced pulmonary edema. [Ann Emerg Med. 2003;41:251-256.]