After many years of unsuccessful conservative treatment 16 patients suffering from hemicrania are relieved of their pain or are improved by operative treatment. Hemicranial attacks or permanent hemicrania is found to be caused by upper cervical nerve root compression. Vascular compression of C2 (n = 9) or scar tissue surrounding C2 (n = 1) or C3 (n = 1) is the pathology identified in cases of cervicogenic headache or "cluster headache-like" headache. Compression attributable to tumor, prolapsed disc, or spondylotic changes is found to be a cause of permanent headache. Only in those patients with permanent headache are radiological or electrophysiological findings helpful for diagnosis. In patients with hemicranial attacks and compression of nerve root C2 (n = 10) or C3 (n = 1), only vasoactive tests (provoking or relieving pain) or local anaesthesia prove to be helpful in diagnosing and localizing the origin of pain. The operation involves freeing the nerve roots from vascular compression. In two patients the C2 ganglion is resected. Thirteen patients subsequently become pain free. In three patients, hemicrania improves. Four of the 16 patients experience a recurrence of pain after the decompressive operation. After additional thermorhizotomy two patients have no further complaints and one patient has improved. One patient can tolerate his pain with occasional analgesics. The problem of referred pain into the fronto-ocular region is discussed.