Abstract: Objective:To evaluate the applicability of serum cystatin C(Cys C)and ratio of urine microalbumin(mAlb)to creatinine(Cr)for diagnosing early renal impairment in patients with hypertension.Methods:The concentration of serum Cys C was measured by immune transmission nephelometry and urine mAlb was measured by immune turbidimetry method and the concentration of serum Cr and urine Cr were measured by automatic chemisty analyzer in 65 cases of hypertension patients and 58 cases of health adults.Results:The concentration of Cys C and ratio of urine mAlb to Cr in hypertension group were higher than those in health control group,and there had statistical differences between the two groups(P﹤0.01),but no statistical significance about the concentration of serum Cr(P﹥0.05).Conclusions: The negative result of qualitative urine protein can not exclude early renal impairment.Through serum Cys C and urine mAlb/Cr index detection.there has the higher sensitivity and specificity for diagnosing early renal damage with hypertension.