Background: Little case was reported about coronary artery spasm after a mitral valve replacement and concomitant Cox-Maze IV procedure. We reported a case of an adult male who develop right coronary artery (RCA) spasm after a mitral valve replacement with tricuspid valve repair and Cox-Maze IV procedure. Case Report: A 66-year-old male, complaining progressive exertional shortness of breath, was diagnosed as severe mitral stenosis, moderate tricuspid regurgitation, complete right bundle branch block and persistent atrial fibrillation (AF) in our clinic. The patient underwent elective mitral valve replacement, tricuspid valve repair and Cox-Maze IV procedure. 4 h after surgery, a 12-lead electrocardiogram (ECG) showed progressive elevation of ST-segment in the avF and III leads and Troponin-T was over 7000 pg/mL. After 1 h, Troponin-T increased to over 10000 pg/mL and ECG still showed persisted ST-segment elevation in inferior leads. Emergent angiography was performed and intra-coronary administration of nitroglycerin completely relieved the spasm. KEYWORDS mitral valve replacement, Cox-Maze IV, coronary artery spasm