Current definitions of common migraine are not specific and new criteria are needed. Our concept of common migraine was supported by comparing the features of 100 consecutive patients we diagnosed as common migraine, with past series. The features of our patients with common migraine were then compared with 100 cases of chronic daily headache, the only form of “tension headache” that can unequivocally be differentiated from migraine. The features that occurred significantly (P<0.001) more often in patients with common migraine than in those with chronic daily headache, were nausea, vomiting, unilateral site, throbbing quality, photophobia or phonophobia, increase with menstruation, and a family history of migraine. Criteria using these features, as well as other sets of criteria, were evaluated by retrospectively applying them to the patients diagnosed as having common migraine and chronic daily headache.