Two cases of systemic lupus erythematosus (SLE) complicated by pneumonia which resulted in death are reported. The first patient, a 21-year old woman, died of acute diffuse lupus pneumonia; the initial and unusual radiological image of "multiple balloons" progressed within 2 months to terminal interstitial fibrosis. The second patient, a 60-year old woman, died of infection on an interstitial pneumonia which turned into severe fibrosis within 16 months. Acute or chronic lupus pneumonia is uncommon, but it may follow a very serious course. Clinically, true lupus pneumonia must be distinguished from all other types of lung involvement in SLE, such as infection, pulmonary haemorrhage or oedema, iatrogenic pathology, thromboembolic disease, etc. The pathogenetic mechanism of pulmonary lesions directly related to SLE is obscure, although some lung biopsy specimens have shown positive immunofluorescence. Concerning treatment, the initial response to corticosteroid therapy is usually very good, especially in the acute forms of the disease. However, in severe cases immunosuppressive drugs or even plasma exchanges must be added to steroids. For treatment to be rapidly initiated the diagnostic procedures must be completed in the early stages of the disease, involving, when necessary, surgical lung biopsy.