The nervus intermedius (NI) appears to be the main conduit for the associated symptoms of cluster headache (CH) and perhaps for the pain as well. Subtle injury of the facial nerve and NI might initiate mechanisms responsible for CH. Five patients with chronic CH unresponsive to medication underwent surgical decompression of the root exit-entry zone of the facial nerve, and in two patients the trigeminal nerve root was also decompressed. In two patients, the pain syndrome was markedly relieved for as long as two years. In one patient, initial improvement was obscured by narcotic addiction. In two patients, the operation was a failure. The NI was identified as a separate bundle in only one of five patients and decompressions may not have affected that component of the facial nerve.