Eleven children under 16 years of age with purulent pericarditis were seen in one hospital in one year. The condition was always secondary to a septic focus elsewhere, usually staphylococcal pneumonia; its incidence after pneumonia was 0.64%, but this may be an underestimate. Clinical diagnosis can be difficult in patients with pneumonia as the heart is not always enlarged. Persistent or progressive liver enlargement was an important diagnostic feature. The presence of excess pericardial fluid was easily confirmed by echocardiography. Early diagnosis and drainage followed by continuous irrigation with 0.1% povidone iodine solution usually resulted in rapid recovery, but two patients died.