We studied the effect of the administration of different doses of antigen in a model of chronic glomerulonephritis produced in mice by the daily injection of apoferritin. Four groups of mice received intraperitoneal injections of 4 mg apoferritin (group 1), 2 mg apoferritin (group 2), 1 mg apoferritin (group 3), or saline (group 4) daily. Significant proteinuria and the presence of antiapoferritin antibody were demonstrated in mice immunized with apoferritin. The severity of histologic damage and the extent of staining for IgG significantly increased with larger doses of apoferritin. Electron microscopy revealed subepithelial and mesangial electron-dense deposits. Administration of large daily doses of apoferritin to mice results in a reliable model of immune complex glomerulonephritis and crescent formation.