The case history of seven children aged 1 5/12 to 5 9/12 years with non tuberculous bacterial pericarditis, observed in the last 8 years at the University children's hospitals of Basle, Berne and Zurich is reported. The history showed febrile illness of 3--14 days duration, which led to an admission diagnosis of pneumonia, angina or pseudocroup. From the signs of heart failure and cardiomegaly on chest X-ray the differential diagnosis of myocardial disease or pericardial effusion was made. The ECG-changes were uncharacteristic, and a friction rub and pulsus paradoxus was encountered once only. The effusion diagnosis should preferably be substantiated by a non-invasive method (scintigram, echocardiogram) as diagnostic pericardiocentesis does often not allow to aspirate the thick pus through the needle. Diagnostic and therapeutic surgical pericardiotomy with consecutive drainage is therefore mandatory. Halothane should be avoided as an anesthetic for this procedure of hemodynamic reasons. With surgery and antibiotics the recovery rate in our series was 100%, and no pericardial constriction was observed on follow-up 1 to 8 years later.