Abstract: Objective To investigate the clinical significance of complement activation in patients with HBV related glomerulonephritis (HBV-GN).Methods Biopsy-proven HBV-GN patients admitted in our hospital were retrospectively recruited.Decreased serum C3 level was defined as C3 ＜ 85 mg/dL.According to the serum C3 level,the patients were divided into the decreased serum C3 group and normal serum C3 group,and the pathological and clinical differences were compared between the two groups.According to the intensity of C3 deposition in the kidney,patients were divided into negative and positive group,and the pathological and clinical differences were compared.Results In this study,29 HBV-GN patients were recruited.There were 18 (62.07％) patients in the normal serum C3 group and 11 (37.93％) patients in the decreased serum C3 group.Compared with the patients with normal serum C3 level,patients with decreased serum C3 level had higher serum creatinine level,lower eGFR level,severer mesangial proliferation and renal interstitial fibrosis (P ＜ 0.05).There were 9 (31.03 ％) patients with negative C3 deposition in the kidney,and 20 (68.97％) patients with positive C3 deposition.Higher cholesterol,higher IgG levels,lower serum albumin,serum C 3 levels,lower eGFR level,severer glomerular sclerosis,inflammatory cell infiltration in renal interstitial,renal tubular atrophy,and renal interstitial fibrosis were associated with a higher grade of C3 deposition in the kidney (P ＜ 0.05).Conclusion There are different levels of complement activation in patients with HBV-GN.Local and systemic complement activation is associated with decreased renal function.Complement activation may be involved in the development of HBV-GN.