Objective To analyze the expression and regulation of components of intrarenal renin-angiotensin system (RAS) and the correlation between intrarenal angiotensin Ⅱ (Ang Ⅱ) expression and clinicopathological injury index in primary IgA nephropathy patients. Methods Expressions of intrarenal RAS components were assessed by immunohistochemistry staining (IHCS). Correlation among intrarenal RAS components and of intrarenal Ang Ⅱ expression with blood pressure, estimated glomerular filtration rate (eGFR), 24-h urinary protein and Katafuchi score in 36 primary IgA nephropathy patients were examined. Results There were positive correlations between positive IHCS area of intrarenal renin and Ang Ⅱ (r=0.43, P＜0.01), angiotensiongen and Ang Ⅱ (r=0.34, P＜0.05). There was negative correlation between positive IHCS area of intrarenal Ang Ⅱ and eGFR (r=-0.61, P＜0.01). There was positive correlation between positive IHCS area of intrarenal Ang Ⅱ and pathological chronicity index (ρ=0.39, P＜0.05), index of interstitial cell infiltration (ρ =0.52, P ＜0.05). Conclusion Expression of intrarenal Ang Ⅱ is positively correlated with expression of intrarenal renin and angiotensinogen, and plays an important role in kidney fibrosis in primary IgA nephropathy.