The objective of this study was the evaluation of clinical, demographic and treatment-associated mortality factors in patients with diffuse alveolar haemorrhage (DAH) associated with systemic lupus erythematosus (SLE). Clinical, laboratory test, SLEDAI-2K, predictors of mortality (APACHE II) and different treatments including cyclophosphamide, methylprednisolone and rituximab were evaluated in SLE patients who were diagnosed with DAH, to determine potential association with mortality. Twenty-nine episodes of DAH in 22 SLE patients were included (one patient with four episodes, four patients with two episodes (seven recurrences)), 15 died. Mean age was 25.1 years and 1.5 years of SLE evolution with haemoglobin drop 3.4 g/dl. In 4 of 22 patients, the DAH diagnosis was confirmed by autopsy. Six episodes were in patients under 18 years of age (2 patients with recurrence). DAH was the initial manifestation of SLE in 10 patients. Of the 22 patients, 17 were women and 22/29 had DAH episodes. Dyspnoea and nephritis occurred in all patients, less common were arthritis (75.9%) and fever (65.5%); haemoptysis was present only in 44.8%. Through evaluation of all included factors, only thrombocytopenia, renal failure, requirement for mechanical ventilation and high APACHE II were associated with higher mortality. Cyclophosphamide use was associated with less mortality (not statistically significant).