BACKGROUND: Diffuse alveolar haemorrhage (DAH) is a life-threatening condition due to immune and non-immune causes. Early identification of an underlying immune disorder is essential in order to initiate appropriate treatment. OBJECTIVE: The purpose of this study was to identify early predictive factors of an immune cause of DAH. METHODS: We conducted a retrospective study of 76 immunocompetent patients with DAH to identify early predictive factors of immune-related DAH using clinical, radiological and routine biological data available in the first 24 h after hospital admission. RESULTS: Multivariate analysis identified 4 parameters which were independently associated with immune-related DAH: (1) onset of first respiratory symptoms ≥11 days, (2) fatigue and/or weight loss during the month prior to presentation, (3) arthralgias or arthritis and (4) proteinuria ≥1 g/l. A simplified scale was constructed using these variables, with an area under the receiver operating characteristic curve of 0.913, for the diagnosis of immune-related DAH. CONCLUSIONS: A simple diagnostic scale can be used to identify an immune-related cause of DAH in immunocompetent patients and may help guide treatment decisions such as initiation of steroid therapy on the day of admission.