Bilateral phrenic neuropathy is a rare cause of acute ventilatory failure posing both diagnostic and therapeutic difficulties. We report the case of a 55-years-old diabetic male presenting with acute onset orthopnea. Clinical and radioscopic evaluations suggested bilateral diaphragmatic paralysis, electroneuromyographic studies revealed bilateral acute phrenic neuropathy, and cerebrospinal fluid examination found albuminocytologic dissociation. The administration of high-dose intravenous immunoglobulin was followed by prompt improvement. During the next months the symptoms continued to regress. There were no recurrences. We consider the patient had a spatially limited form of acute inflammatory demyelinating polyradiculoneuropathy. The case underlies the importance of considering an immune mediated etiology in patients with acute bilateral phrenic neuropathy. To the best of our knowledge no similar case has been reported.