The correlation between the biochemical markers of platelet activation and serotonin in migraine was investigated. The beta-thromboglobulin (beta-TG), platelet factor 4 (PF-4) and serotonin levels in 105 patients with migraine were measured. The results confirmed an increase in beta-TG and PF4 levels and a reduction in serotonin levels during the migraine attacks. However, we did not find a significant correlation between these fluctuations. These findings suggest the existence of extraplatelet mechanism in the pathophysiology of migraine.