Abstract Objectives Immunoglobulin A vasculitis (IgAV) is a small-vessel vasculitis most frequently benign in children while more severe in adults. We aimed to study the impact of age on presentation and outcome of adult IgAV. Methods We conducted a nationwide retrospective study including 260 IgAV patients. Patients were divided into four quartiles according to the age at IgAV diagnosis: <36, 36 ≤ age < 52; 52 ≤ age < 63 and ≥63 years. Comparison of presentation and outcome were performed according to age of disease onset. Results Mean age at diagnosis was 50.1 (18) years and 63% were male. IgAV diagnosed in the lowest quartile of age was associated with more frequent joint (P < 0.0001) and gastrointestinal involvement (P = 0.001). In contrast, the oldest patients had more severe purpura with necrotic lesions (P = 0.001) and more frequent renal involvement (P < 0.0001), with more frequent haematuria, renal failure, higher urine protein excretion and more frequent tubulointerstitial lesions. Patients were treated similarly in all groups of age, and clinical response and relapse rates were similar between groups. In the 127 treated patients with follow-up data for >6 months, clinical response and relapse rates were similar between the four groups. Median follow-up was of 17.2 months (9.1–38.3 months). Renal failure at the end of follow-up was significantly more frequent in the highest quartile of age (P = 0.02), but the occurrence of end-stage renal disease was similar in all groups. Last, overall and IgAV-related deaths were associated with increase in age. Conclusion Aging negatively impacts the severity and outcome of IgAV in adults. Younger patients have more frequent joint and gastrointestinal involvement, while old patients display more frequent severe purpura and glomerulonephritis.