Headache is merely a symptom, and clinically our efforts should concentrate on tracing the course of the headache in the give case, though often we get no farther than to establish the dynamics of the headache and adopt the treatment accordingly.In a preceding paper (i) it was reported that 63 % of the patients in our neurological clinic complained of headache. About the various forms of headache, among 459 cases of paroxysmal headache migraine occurred in 81 %, allergic headache in 6 %, histamine hemicrania in 4 %, and other, partly unclassifiable, forms in 8 %.As to the incidence of migraine, in a neurological patient material it was 3 %, in a general medical 2 %, and in a gynecological material it was 10 %.The appearance of headache requires an active eliciting factor, endogenous or exogenous, and often these factors, which are innumerable, fail to be recognized so that the headache apparently sets in spontaneously. Considering migraine, for instance, the factors eliciting an attack are so many and so different as to give the impression that their only mutual feature is just their abUity to elicit an attack of migraine.In order to illustrate this lack of homogenity it will be sufficient to mention such different factors as hormonal dis-