Haemothorax is a well-recognized sequela of chest trauma, ruptured aortic aneurysm, and inadvertent puncture of intrathoracic vessels during cannulation or intercostal chest drain insertions, as well as numerous intrapulmonary, pleural and mediastinal conditions. However, massive idiopathic haemothorax occurring in an otherwise healthy subject is, extremely rare, with only two cases reported so far. We add another case and review the scanty literature for identifiable aetiological and predisposing pathological factors. The pathogenesis is discussed and the management outlined, emphasising the diagnostic and therapeutic value of thoracoscopy.