We report on a case of diffuse alveolar haemorrhage in a Chinese woman due to methimazole-induced antineutrophil cytoplasmic antibodies. A literature search for anti-thyroid drugs associated with antineutrophil cytoplasmic antibody-induced diffuse alveolar haemorrhages is reviewed. Diffuse alveolar haemorrhage is a rare complication of thiourea agents and the treatment often requires corticosteroids or other immunosuppressants, together with withdrawal of the causative agent.