To elucidate the relationship between glomerular deposition of protein S (PS) and renal lesions or dysfunction, 30 patients with various glomerulopathies were examined. Glomerular PS deposition was found in 20 patients (group A), and other 10 patients showed no deposition (group B). PS was found mainly along the capillary loops and segmentally in the mesangium. Group A showed significantly more severe proteinuria than group B (p < 0.05). Group A patients showed significant decreases in glomerular filtration rate (p < 0.01). Patients in group A had significantly lower plasma levels of plasmin-alpha<sub>2</sub>-plasmin inhibitor complexes (p < 0.05) and thrombin-antithrombin III complexes (p < 0.01) than those in group B. Group A showed significant decreases in the mean values of plasma total PS (p < 0.01) and protein C (PC) antigens (p < 0.01) and C4b-binding protein (C4bp; p < 0.05) as compared with group B patients. There was a positive correlation between plasma PS and C4bp (p < 0.02). Histologically, group A showed a significantly higher incidence of glomerular deposition of factor XIII (subunit a), alpha<sub>2</sub>-plasmin inhibitor, PC (p < 0.05), and C4bp (p < 0.01). The present study demonstrates that glomerular PS deposition indicates the existence of PC and C4bp in the glomeruli and suggests that the glomerular PS deposition may modify the activation of fibrinolytic and coagulation systems within the glomeruli in various glomerulopathies.