Purulent pericarditis is diagnosed when pus is drained from the pericardial space or when bacteria are cultured from the pericardial fluid. This rare disease is often diagnosed late, when severe hemodynamic compromise develops due to pericardial tamponade. It is usually a complication of pneumonia, especially if there is empyema as well, and often follows chest surgery or chest wall infections. It sometimes appears in patients with septicemia, especially when they are debilitated or immuno-compromised. Diagnosis is aided by echocardiography. Pericardiocentesis and drainage of the pus, as well as prolonged antibiotic treatment, are mandatory. Delay in diagnosis and treatment often results in death. Some surviving patients may develop constrictive pericarditis and require pericardiectomy. We report a 73-year-old man with pulmonary lymphoma who suffered from purulent pericarditis secondary to sepsis with methicillin-resistant Staphylococcus aureus. Pericardial drainage and appropriate antibiotic treatment eventually resulted in complete recovery.