The authors present a case of an 85-year-old woman known to suffer from severe congestive heart failure who presented with dyspnea and a unilateral infiltrate in the right lung on chest x-ray. Following clinical judgment, she was diagnosed with unilateral pulmonary edema and was treated accordingly, with rapid improvement of symptoms and disappearance of the infiltrate within 12 hours. The patient had been hospitalized many times during the previous years with pulmonary edema affecting both lung fields. Unilateral pulmonary edema is an unusual clinical condition that has been reported as a manifestation of left heart failure, mostly affecting the right lung. The authors emphasize the possible presentation of unilateral pulmonary edema in a patient with heart failure and recurrent bilateral pulmonary edema.