28 patients with chronic renal failure (C. R. F.), aged 9 to 67 years old, were administered oral carbonaceous adsorbent (AST-120) as conservative therapy. Patients were divided into 3 groups according to their levels of serum creatinine (S-CRTN) . 10 patients of early stage of C. R. F., S-CRTN below 3.9 mg/dl, were classified as group A. 13 patients of value of S-CRTN between 4.0 to 7.9 mg/dl were classified as group E and 5 patients of value of S-CRNT over S mg/dl were classified as group C. Clinical courses were followed by several biochemical parameters before and after administration of the oral adsorbent. The results were evaluated by reciprocal S-CRTN versus time plots and analysis of Wilcoxon test (w-test). 7/10 patients (70%) in group A were revealed effective to oral adsorbent therapy and w.test was significant (P<0.05) . Mean duration of adminsistration of adsorbent was 15.6 ±2.7 (Mean±SENI) months.11/13 patients (84.6%) in group P were effective and w-test was significant (P<0.01) Mean duration, 16.5±2.9 months. 3/5 patients (60%) in group C were effective but w-test was not significant. In patients of group R and C, introduction of hemodialysis were postponed about 2 times longer than control patients of C. R. FF with natural course. We conculuded that oral adsorbent (AST-120) was effective to patients of C. R. FF in conservative therapy, and observed satisfactory outcome even in patients of early stage of C. R. F. like group A.