Alveolar haemorrhage (AH) can be a mild or life-threatening manifestation of antineutrophil cytoplasm antibody (ANCA)-associated vasculitides (AAV), but its prognostic impact and specific characteristics remain controversial. Our objective was to determine the prognostic value of AH in this context. AH episodes that occurred, between 1991 and 2010, in AAV patients entered in the FVSG database were retrospectively analysed. Data on AH characteristics and outcome measures were collected on a specific form. Among the 80 cases analysed, AAV were 61.25% granulomatosis with polyangiitis (GPA) (Wegener), 26.25% microscopic polyangiitis (MPA), 10% Churg-Strauss syndrome and 2 (2.5%) unclassified. Mild or severe haemoptysis alone, or together with other clinical symptoms was present in 77 (96.2%) patients before AAV diagnosis. Among 10 (12.5%) patients requiring mechanical ventilation, 4 had prior minor haemoptysis before abundant AH. Sixty-one (76.3%) patients had concomitant active rapid crescentic glomerulonephritis causing renal insufficiency (pulmo-renal syndrome): 37/49 GPA (Wegener) (75.5% of all GPA (Wegener)), 19/21 MPA (90.4% of all MPA), 3/8 had CSS and 2/2 had unclassified vasculitis. The mean AH-to-treatment-onset interval was 5.9 days. Mean follow-up was 7.3 years. Forty-seven (58.8%) patients relapsed: 23 with AH and with (13) or without (10) other organ involvement, 24 with non-AH manifestation(s). Three patients underwent kidney transplantation. Sixteen (20%, 8 GPA (Wegener) and 8 MPA) patients died. No death resulted directly from the initial AH; 14 (87.5%) patients with pulmo-renal syndrome died. As previously demonstrated by the Five-Factor Score, AH alone is not predictive of poor prognosis, unlike kidney involvement, which dictates a poor outcome.