A possible agent for human non-A-E hepatitis has been identified and named hepatitis G virus (HGV). HGV is also a flavivirus, and the clinical characteristics and risk factors of HGV infection may be similar to those of hepatitis C virus infection. Hepatitis C virus infection may manifest as a primary glomerulonephritis. The aim of this study is to evaluate the prevalence of serum HGV RNA in 98 adult patients with biopsy-proven glomerular diseases. We found that only 3 patients (3%) out of 98 with primary glomerulonephritis had HGV RNA. One of 59 (1.7%) healthy controls was serum HGV RNA positive (p > 0.05). The prevalence of serum HCV RNA was low in the patients with primary glomerulonephritis.