Pyopneumopericardium is a rare condition with high mortality. Most cases are the result of a fistulous communication between the pericardial cavity and the gastrointestinal or the respiratory tract. Rarely, the condition may arise spontaneously. We describe a 7-year-old boy, a diagnosed case of acute lymphoblastic leukemia, on chemotherapy who developed pyopneumopericardium without pneumothorax and responded well to conservative management.