Adrenocortical hormones have been used for nephrotic syndrome from 1950. But effects of these drugs in coagulation and fibrinolysis are unknown in detail. We studied the effect of prednisolone in a patient with nephrotic syndrome. Protein C increased remarkably after administration of prednisolone 40 mg/day and then decreased in parallel with the dose of prednisolone. Factor X increased more slowly than Protein C. On the other hand, we couldn't find increase of Protein S. Our results indicate that prednisolone have anticoagulant effect by promotion of production of Protein C.