OBJECTIVE: To compare the incidence of hepatitis B virus ( HBV)- associated membranous nephropathy (HBVMN) before and after universal HBV vaccination and to identify factors underlying the change. METHODS: This study included 471 hospitalized children with nephrotic syndrome (NS) and 488 long-term follow-up hepatitis B surface antigen (HBsAg)- carrier children. Horizontal transmission (negative maternal HBsAg status) of HBVMN and HBV was assessed, and the incidence of HBVMN was compared before and after initiation of the universal HBV vaccination program started in 1984. RESULTS: The frequency of HBVMN in children with NS was 11.6 % between 1974 and 1984, 4.5% between 1984 and 1994, 2.1% between 1994 and 2004, and 0% between 2004 and 2009. Similarly, the number of HBsAg- seropositive children with NS (mainly via horizontal infection) decreased after universal vaccination. The prevaccination frequency of HBV horizontal transmission in chronic HBsAg carriers from the general population was 36.5% compared with 5% in the postvaccination period. The incidence of HBVMN in these carriers revealed a parallel decline. CONCLUSIONS: Our results revealed a significant decrease in the frequency of HBVMN in children with NS and in long-term follow-up HBsAg carriers. Children with HBVMN are primarily infected with HBV via horizontal transmission; thus, the significant reduction in horizontal transmission in HBsAg-carrier children in the general population after universal HBV vaccination may explain the reduction of HBVMN in the vaccinated population. These findings confirm the effectiveness of HBV vaccination on reducing the incidence of HBVMN, possibly through a significant decline in horizontal HBV infection. ; 醫學系小兒科 ; 醫學系 ; 醫學院 ; 期刊論文