Two cases of Reexpansion pulmonary edema (RPE), an uncommon complication of the treatment of chronic lung collapse secondary to pneumothorax or pleural effusion, are described. RPE is generally unilateral and occurs when the lung is rapidly reexpanded by active evacuation of large amounts of air or fluid. Nevertheless, both cases observed confirm that RPE can be seen when the pulmonary collapse is of short duration and the lung is reexpanded without suction. The pathogenesis of RPE is still unclear and is probably multifactorial. Implicated in the etiological process of RPE are chronicity of collapse, technique of reexpansion, increased pulmonary vascular permeability, airway obstruction, loss of surfactant, and pulmonary artery pressure changes. In the observed cases RPE appeared unexpectedly and dramatically, which is typical of the condition. The edema progressed for 24-48 hours, although it may persist for 4-5 days. Therapy was supportive and proportional to the severity of the clinical picture. Both needed mechanical ventilation, while only in case 1 was a hemodynamic support applied. Since the outcome is still fatal in 20% of cases, physicians treating chronic lung collapse must be aware of the possible causes and try to prevent the occurrence of this complication.