Membranous nephropathy (MN) may also be secondary to many other diseases (e.g., infections, drugs, neoplasms and autoimmune diseases). In this study, the presence of Helicobacter Pylori (H. pylori) antigen was investigated in renal tissue from needle biopsy samples, and the prevalence of H. pylori infection and the effects of H. pylori eradication on proteinuria level in patients with MN will be investigated.