The following case is reported as an example of a little known complication of primary tuberculous infection.A female child aged two and a half years was admitted to Southmead Hospital, Bristol, on Dec. 3, 1946. Her parents and sister were in good health I 98^F., and the pulse 120 per minute, regular, but of poor volume. The cardiac impulse was diffuse and wavy and the apex beat was in the sixth left interspace in the anterior axillary line. A loud pericardial friction rub was audible all over the precordium; the heart sounds were muffled, but there were no murmurs. There were no signs of