We report a patient manifesting severe hypoventilation resulting from diaphragmatic paresis secondary to sarcoid. A 34yr-old female presented with chest pain. Chest radiograph revealed hilar adenopathy and left pleural effusion; computed tomography scan showed a 2-cm solid lesion in the aorto-pulmonary window. Bronchoscopy and thoracentesis failed to further identify the nature of the lesion. An episode of aspiration resulted in cardiopulmonary arrest, necessitating cardiopulmonary resuscitation. Electrodiagnostic findings were consistent with bilateral phrenic neuropathy with axon loss, suggesting a poor prognosis. Biopsy via mediastinoscopy revealed noncaseating confluent granulomas with many multinucleated epithelioid histiocytes consistent with the diagnosis of sarcoidosis. Eight months after initial diagnosis and immunosuppressive treatment, the patient was successfully extubated and became ambulatory. Upon tapering her prednisone, however, she became dyspneic and manifested hypoventilation secondary to muscle weakness. Her corticosteroids were increased, but she eventually died of an opportunistic lung infection 2 yr later. This case establishes phrenic neuropathy and peripheral polyneuropathy secondary to neurosarcoidosis as a cause of respiratory failure. It also illustrates the utility of phrenic and diaphragmatic electrodiagnosis in the evaluation as well as prognostication of such lesions.