Tuberculous pericarditis is an exceedingly rare but a well-described extra-pulmonary manifestation of tuberculosis (TB) infection in Hong Kong. An 82-year-old woman with a known history of diabetes mellitus, hypertension and hyperlipidaemia was admitted for congestive heart failure. Routine echocardiographic study during admission revealed a massive pericardial effusion (~4 cm in thickness) but with no tamponade effect. Pericardiocentesis was performed and 1.6 L of heavily blood stained fluid was drained. All tumour and auto-immune markers were unremarkable. A whole body positron emission tomography-computer tomography (PET-CT) scan was then performed and showed an increased fluorodeoxyglucose uptake in the entire pericardium with no sources of possible malignancy identified. Rapid acid fast bacilli culture and Genprobe examination of the pericardial fluid then demonstrated the growth of Mycobacterium tuberculosis. She was started on anti-TB medications and tolerated them well. Follow-up echocardiographic study showed no re-accumulation of pericardial fluid.