BACKGROUND IgA vasculitis nephritis (IgAVN) is a common form of secondary glomerulonephritis and can occur in patients of any age. Our study was designed to reveal renal histopathological manifestations of children and adults with IgAVN and to explore the potential pathogenesis of IgAVN. METHODS Sixty-one pediatric and seventy adult patients with IgAVN were enrolled altogether, and all of them underwent kidney biopsies. General information, laboratory parameters, and renal histopathological manifestations of all patients were analyzed. RESULTS (1) Diabetes, hypertension, and various levels of proteinuria made no difference between children and adults. (2) Global sclerosis and tubular atrophy/interstitial fibrosis occurred more commonly in adults than in children (24.29 % vs 8.20 %, 65.71 % vs 9.84 %, respectively) (P < 0.05). (3) The immunofluorescence deposition of complement C3 was more apparent in adults (P < 0.05). (4) The deposition of IgA, IgG, IgM, and C3 in kidneys was unrelated to the pathological types. (5) The deposition of IgG or IgM was related to the deposition of IgA or C3 in children and adults (P < 0.05). CONCLUSIONS Chronic kidney injury occurred more commonly in adult IgAVN patients compared to pediatric IgAVN patients. Immunoglobulin and complement deposits in kidneys were independent of the types of renal pathological injury. Additionally, IgG and IgM were probably involved in IgAVN pathogenesis.