OBJECTIVE: The aim of present study is to compare ventricular and supraventricular arrhythmia incidences in subjects with and without mitral valve prolapse (MVP) syndrome and to examine if an association exists between ventricular arrhythmias and repolarization parameters in patients with MVP syndrome. METHODS: This cross-sectional study involved 41 subjects with MVP Syndrome and 41 subjects with palpitation but without MVP (control group). All subjects were subjected to lead-electrocardiogram, transthoracic echocardiography, and 24-h Holter monitoring to identify repolarization abnormalities, structural abnormalities, and supraventricular and ventricular arrhythmias. The QRS width, QTC interval, and Tpeak-Tend intervals were measured for each participant. RESULTS: The number of subjects who had premature ventricular contractions (PVCs), couplets, and non-sustained ven- tricular tachycardia (NSVTs) was significantly higher in the MVP group compared to the control group. Left ventricular end- systolic diameter (LVESD) and left ventricular end-diastolic diameter (LVEDD) and left atrial diameter were also significantly higher in the MVP group than the control group. QRS width and Tpeak-Tend interval were also significantly higher in subjects with MVP than the controls. Correlation analysis showed a positive correlation between the severity of mitral regurgitation (MR) and the number of PVCs and couplets, while there was a significant correlation between left atrium (LA) diameter and the number of the PVCs and NSVTs. CONCLUSION: Subjects with MVP experience ventricular arrhythmias more often including PVCs, couplets, and NSVTs compared to subjects without MVP. LVESD, LVEDD, LA diameter, QRS width, and Tpeak-Tend interval were increased in MVP subjects than those without MVP. There is an association between the severity of the MR and the frequency of the PVCs, couplets, or NSVTs.