Subarachnoid-pleural fistula after routine thoracotomy is a rare complication but a very serious problem. Twenty one cases have been reported in the literature. We report a care of subarchnoid-pleural fistula that dveloped after the esecation of posterior mediastinal neurogenic tumor. The patient presented with large amount of clear pleural fluid with mild headache and dizziness. Surgical intervention following a trial of conservative therapy was undertaken because we strongly suspected subarachnoid-pleural fistula. A dural tear was found at the level of resected intercostal nerve root. The dura was closed by way of direct suture and fibrin glue. In this case, the recognition of subarachnoid-pleural fistula formation is difficult because the patient had not presented any neurologic deficit.