The identification of antigens in the autoimmune diseases is a primary point to elucidate the pathogenesis of disease. Here, we propose an "in vivo" proteomics approach to identify the antigens of auto-antibodies in membranous glomerulonephritis. In this approach, podocyte proteins resolved by two-dimensional electrophoresis were semidry blotted to nitrocellulose membrane. Then the antibodies eluted from microdissected glomeruli and serum samples were used as a probe for the detection of podocyte antigens and characterized by means of mass spectrometry. These combined methods allowed us to identify six new antigens in membranous glomerulonephritis.