Impaired sympathovagal balance, the main pathophysiological mechanism under the vasovagal syncope (VVS), may play a role on platelet sizes. Although it has been shown that mean platelet volume (MPV) is increased in patients with vasovagal syncope, its nature in syncope subgroups is unknown. Herein, we aimed to compare MPV values among patients with different head-upright tilt-table (HUTT) test results. Patients who underwent HUTT test were analyzed retrospectively. Patients' demographic data

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... their complete blood count samples within the 24h of test were obtained from hospital data network. Patients were divided into 4 groups according to their HUTT test results; group I: cardioinhibitory type, group II: mixt type, group III: vasodepressor type and group IV: negative result. There were no statistical differences regarding the age and gender between the groups. There was statistically significant difference between groups, regarding the values of MPV, platelet distribution width (PDW), hemoglobin and hematocrit. In patients with vasodepressor type response, MPV was statistically significantly higher compared with control and other groups (p<0.001), whereas hemoglobin and hematocrit values were significantly lower compared with the control group. We showed that MPV is increased in vasodepressor type syncope group, whereas it is decreased in cardioinhibitory and mixt type response group. However, further randomized prospective studies are warranted.