We report a case of azathioprine-induced haemorrhagic alveolitis, in a 14-year-old boy, after renal transplantation. On day 25 the patient developed haemoptysis, fever and hypoxaemia. Chest X-ray showed diffuse reticulo-nodular shadows in both lung fields. Bronchoalveolar lavage samples were haemorrhagic and demonstrated a relative neutrophilia and a mild lymphocytosis, with a normal CD4/CD8 ratio. Azathioprine was discontinued on day 26. The patient required mechanical ventilation for 4 days. A positive leucocyte migration inhibition test and the recurrence of the symptoms after a second short course of azathioprine therapy suggested a cell-mediated mechanism. This patient is, to our knowledge, the first child to suffer from azathioprine-induced pulmonary haemorrhage.