Introduction: long-term observation of patients with ANCA-associated vasculitis (AAV) allows the identification of different longitudinal patterns of ANCA levels during follow-up. This study aimed to characterise these patterns and to determine their prognostic significance. Methods: all ANCA determinations performed in two university hospitals along a 2-year period were retrospectively reviewed. Patients were included in the analysis if they had high titers of anti-myeloperoxidase (anti-MPO) or anti-proteinase 3 (anti-PR3) antibodies at least once, they had ≥5 serial ANCA determinations, and they had AAV diagnosed by biopsy or ACR classification criteria. Patients’ time-course ANCA patterns were classified as monophasic, remitting, recurrent or persistent. Associations between ANCA patterns and prognostic variables (relapse rate and renal outcome) were analysed by univariate and multivariate statistics. Results: A total of 99 patients (55 with microscopic polyangiitis [MPA], 36 with granulomatosis with polyangiitis [GPA], and 8 with eosino¬philic granulomatosis with polyangiitis) were included. Median follow-up was 9 years. Among patients diagnosed with MPA or GPA, recurrent or persistent ANCA patterns were associated with a higher risk of clinical relapse (HR 3.7 [95% CI 1.5-9.1] and HR 2.9 [95% CI 1.1-8.0] respectively), independently of clinical diagnosis or ANCA specificity. In patients with anti-MPO antibodies, the recurrent ANCA pattern was associated with worsening renal function (OR 5.7 [95% CI 1.2-26.0]). Conclusion: Recurrent or persistent ANCA patterns are associated with a higher risk of clinical relapse. A recurrent ANCA pattern was associated with worsening renal function in anti-MPO-associated vasculitis.