To study the interaction of positively charged antibodies in immune complexes with the fixed negative charge on the glomerular capillary wall, chemical cationization of antibody was accomplished with the maintenance of antigen-binding activity. These cationized antibodies bound rapidly to glomeruli but did not persist. Large-latticed immune complexes formed with these cationic antibodies showed rapid deposition and persistence in renal glomeruli, even when administered in small doses. Electron-dense deposits were present at the anionic sites in the glomerular basement membrane at 1 min and 1 h, with extensive subendothelial deposits present from 12 to 72 h. By 14 d, the deposits were seen in the subepithelial region and the glomerular mesangium. The administration of small-latticed immune complexes prepared with cationized antibody revealed initial deposition without persistence in glomeruli in a manner similar to cationized antibodies alone. Thus, the positive charges on antibodies in immune complexes contribute to the deposition and persistence of the complexes in glomeruli, particularly in the subendothelial area.