Purulent pericarditis with cardiac tamponade caused by community-acquired methicillin-resistant Staphylococcus aureus is rare and fatal. There are limited data in children in the current antibiotic era, and available reports usually involve patients with immune dysfunction and prior thoracic instrumentation or has a thoracic focus of infection. Rapid recognition and treatment are paramount in the survival of patients. We report a case of purulent pericarditis with cardiac tamponade secondary to community-acquired MRSA in a previously healthy 10-month-old male infant who presented with fever, pallor, shock, and cardio-respiratory distress. CBC showed leukocytosis with neutrophilia, markedly elevated inflammatory markers, and cardiomegaly on chest radiography. The ECG showed diffuse concave ST-segment elevation, low QRS voltages on precordial leads, and electrical alternans consistent with pericarditis with probable significant pericardial effusion confirmed by 2D echocardiography with note of cardiac tamponade. He was managed effectively with pericardiostomy in combination with a 4-week course of vancomycin. Blood and pericardial fluid culture grew MRSA. This case underscores the organism’s lethality and its potential to infect immunocompetent children without predisposing factors. The value of early recognition, prompt initiation of treatment and management is of utmost importance.