A 34 year old women was admitted to the hospital with a 9 year history of intermittent haemoptysis associated with increasing breathlessness. A working diagnosis of lymphangioleiomyomatosis was made, based on clinical, radiological and histological findings. Three years later, the patient was admitted to hospital with worsening haemoptysis, which rapidly progressed and resulted in death from massive pulmonary haemorrhage. Postmortem examination and histology revealed findings consistent with multiple mesenchymal cystic hamartomas of the lungs. This is a rare condition which has previously been described as having a good prognosis. This case is the first fatality resulting directly from the disease to be reported.