Objective To inverstigate the values of serum cystatin C(SCysC) concentration in diagnosis of early diabetic nephropathy.Methods SCysC concentration and urinary albumin excretion(UAE) andβ_(2)-MG were measured in 65patients with diabetes mellitus by partical-enhanced turbidimetric immunoassay.Results SCysC was positively correated with UAE or β_(2)-MG.Conclusion SCysC is a useful indicator for diagnosis of early diabetic nephropathy and is a more simpler and rapid convenient marker.