Mitral regurgitationmay develop due to left ventricular (LV) remodeling within 3months following acute myocardial infarction (AMI) and is called ischemic mitral regurgitation (IMR).Ischemic preconditioning (IPC) has been reported as the most important mechanism of the association between prior angina and the favorable outcome. The aim of this study was to investigate the effect of prior angina on the development and severity of IMR at 3rdmonth in patients with ST elevation MI (STEMI). Fourty five (45) patients admitted with STEMI and at least mild IMR, revascularized by PCI were enrolled. According topresence of prior angina within 72h before STEMI, patients were then divided into two groups as angina (+) (n:26; 58%) and angina (-) (n:19; 42%). All patients underwent 2D transthoracic echocardiography at1st, 3rddays and 3rdmonth. IMR was evaluated byproximal isovelocity surface area (PISA) method: PISA radius (PISA-r), effective regurgitant orifice area (EROA), regurgitant volume (Rvol). LV ejection fraction (EF %) was calculated by Simpson's method. High sensitive troponin T (hs-TnT), creatine phosphokinase myocardial band (CK-MB) and N-terminal pro-brain natriuretic peptid (NTpro-BNP) levels were compared between two groups. Although PISA-r, EROA and Rvol were similar in both groups at 1stand 3rddays, all were significantly decreased (p = 0.012, p = 0.007, p = 0.011, respectively) and EF was significantly increased (p< 0.001) in angina (+) group at 3rdmonth. NTpro-BNP and hs-TnT levels at 1stday and 3rdmonth were similar, however CK-MB level at 3rdmonth was found to be significantly lower in the angina (+) group (p = 0.034). At the end of the 3rdmonth, it was observed that the severity of IMR evaluated by PISA method was decreased and EF increased significantly in patients who defined angina within 72h prior to STEMI, suggesting a relation withIPC.