An attempt was made through a study of 20 patients to determine the particular type of situation which precipitates attacks of migraine headache. Precipitating events were found to consist of situations which elicited rage and resentment in the patient to which he was unable to give full expression, and occurring at a time when the patient was under a high degree of strain and tension. In 2 cases, exptl. induction of psychologic stress brought about a typical migraine attack. It is concluded that "the migraine attack may be considered one of the phases of an inappropriate protective or adaptive reaction involving cranial circulatory apparatus which is manifest when the subject has reached the limit of his capacity to tolerate tension, hostility, frustration, and fatigue." Protocols from illustrative case histories are included.