The present study was planned to investigate the autonomic nervous system (ANS) function in 60 chronic migraine (CM) patients in order to establish the degree of the autonomic dysfunction and which division of the ANS is more disturbed. The sustained handgrip test was pathologic in 98,3% CM patients as a result of a sympathetic vasoconstriction disturbance. The heart rate responses to deep breathing and 30/15 ratio had pathological values in the majority of cases (86,7% vs. 80,0% respectively) revealing an insuffi ciency of cardiac parasympathetic vagal mechanisms in CM. In ¾ of CM patients the autonomic function testing was severely abnormal according to the Ewing’s classifi cation (1992). Our results demonstrate ANS dysfunction, with hypoactivity of both the sympathetic and parasympathetic nervous system, which might be an important pathophysiological mechanism of this disease.