Massive, recurrent haemoptyses requiring blood transfusions occurred in a patient who had been diagnosed as having pulmonary thromboembolism 3 months earlier. To the authors' knowledge this is the first case report of this kind, in which massive haemoptyses were proved to be caused by large bronchopulmonary collaterals that had developed in the infarcted lung segments affected by embolism. Selective embolization of the collaterals proved to be therapeutic and life saving.