Twenty-one diabetic nephropathy patients with normal serum BUN(Blood Urea Nitrogen), creatinine levels and ten chronic renal failure patients with abnormal high BUN, creatinine levels were investigated to evaluate the renal function change after long term herb medicine administration. The hospitalized patients were administrated three times a day with herb medicine, which were prescribe frequently in practical oriental medicine such as many hospital and local clinics. Blood Urea Nitrogen, creatinine and glomerular filtration rate (GFR) were measured immediately after 7days medication. Serum BUN, creatinine levels in diabetic nephropathy patients changed from 17.63±4.38㎎/㎗, 1.09±0.26㎎/㎗(mean±SD) of pre-medication levels to 14.13±3.24 1,20±0.37, 14.75±2.21 1.23±0.55, 12.34±2.89 1.18±0.42 at 7th, 14th, 21th days after herb medicine administration respectively. Also 24hr urine total protein changed from 632.25±254.43㎎/㎗ of pre-medication levels to 623.18±231.56㎎/㎗ after herb medicine administration(P>0.05). Serum BUN, creatinine levels and GFR in chronic renal failure patients changed from 67.45±13.86㎎/㎗, 6.74±2.91㎎/㎗, 13.73±4.21㎖/min pre-medication levels to 61.23±17.75 6.43±2.29 15.49±3.56, 58.84±19.36 5.83±2.51 16.38±2.85, 56.39±20.33 5.64±2.52 16.73±3.40 at 7th, 14th, 21th days after herb medicine administration respectively. Therefore, there was not clinically remarkable difference in the serum BUN, creatinine, GFR levels between pre-medication and post-medication in both Group.