Background- Mitral valve prolapse syndrome (MVP) is most common valvular abnormality in young and is correlated with increased frequency of cardiac dysrhythmias and sudden death. The aim of this study was to compare frequency of “early repolarization” in electrocardiogram (ECG) between MVP patients and healthy adults. Methods- In this cross-sectional study, we compared ECG presentations of early repolarization including notch in descending arm of QRS and J-point and/or ST segment changes in 100 patients with MVP with 100 healthy individuals. MVP patients were referred to cardiology clinic with symptoms of palpitation, chest pain or anxiety. Results-The mean age in patients with MVP was significantly less than healthy subjects (29.5 ± 9.3 years versus 31.0 ± 6.9 years in control group, p=0.1967). We detected an early repolarization as a prevalent sign in ECG of patients, which was a notch in descending arm of QRS and/or ST segment or J-point elevation seen in 74% of patients ( 51% in inferior leads and 23% in I and aVL leads) , whilst the same findings was seen in 8 men (8%) in control group (p=0.0001). Conclusion- Early repolarization in ECG presented as a notch in descending arm of QRS and/or ST segment or J-point elevation is more frequent in in young patients with MVP syndrome.