A 77-year-old Japanese woman was introduced to our department for the treatment of acute respiratory failure. She had been treated with medications for hypertension and hyperlipidemia for 7 years and she was prescribed cefadroxil after a dental extraction in the dental clinic. She suddenly developed nausea, headache, rigors, and dyspnea several minutes after the administration of cefadroxil after supper, but then she went to bed. The woman visited a hospital because of severe dyspnea the next morning, and she was introduced and admitted to our hospital for treatment of her respiratory failure. Chest X-ray film and computed tomography on admission showed a butterfly pattern of bilateral infiltrations, and she demonstrated severe respiratory failure. She was treated with mechanical ventilation with positive end-expiratory pressure, discontinuation of all medications, and high-dose corticosteroid, and the treatment was successful. A drug lymphocyte stimulation test for cefadroxil was positive, and an echocardiography, an electrocardiogram, and a Swan-Ganz catheter examination revealed no evidence of heart failure. These results were indicative of drug-induced noncardiogenic pulmonary edema resulting from cefadroxil. Furthermore, she was diagnosed as having intermediate obstructive sleep apnea syndrome by overnight polysomnography. To the best of our knowledge, this is the first case report of drug-induced noncardiogenic pulmonary edema because of cefadroxil complicating obstructive sleep apnea syndrome.