To assess the clinical significance of SGOT/SGPT ratio in 301 cases of primary liver cancer (PLC), 284 cases of liver cirrhosis (LC), 231 cases of chronic active hepatitis (C.A.H.) and 104 cases of acute viral hepatitis (A.V.H.). Tne results were briefly summarized as follows: I. The SGOT/SGPT ratio was 0. 860. 47 in AVH group, I.22+-0.66 in C.A.H. group, 1.48+-0.53 in L.C. grop ad 2.53+-1.17 in PLC group. The highest ratio was observed in PLC group with a mean of 2. 53 which was significantly higher than the mean of other liver disease groups. 2. Th SGOT/SGPT ratio in patients with SGOT activity over 2QO units was higher than those of SGOT activity below 200 units, and the mean SGOT/SGPT ratio in the PLC group was also significantly higher than the mean of other liver disease group. 3. The SGOT/SGPT ratio greater than 3 with a serum GOT above 200 units was almost entirely restricted to patients with pr imary liver cancer. It is concluded from these results that a high SGOT/SGPT ratio greater than 3 in a patisnt with a SGOT above 200 units is highly suggestive of primary liver cancer.