The serum complement titer was messured on the admitted patients of liver disease and other several diseases at the first medical department of Okayama University, Medical School, employing the method used at the American anmy medical school. And the results were as follows. 1. The complete disappearance of complement titer was found in fulminant hepatitis. 2. The average decline of complement titer was found in acute hepatitis. 3. The complement titer showed remarkable decline in chronic hepatitis with a prolonged course and scanty healing tendency. 4. The complement titer was normal in the cases with posthepatic damage. 5. The complement titer showed normal limit or rarely ascent in cholecystopathy. 6. Thecomplement titer showed remarkable decline in livercirrhosis and hepatospleno-disease. 7. The complement titer showed a ascent tendency in hemolytic jaudice. 8. In other diseases, the complement titer showed remarkable decline in erythema and infectious mononucleosis and it showed also decline in nephrit's, Basedow's disease and subacute bacterial endocarditis. 9. The comparative correlation was observed betweem the decline of complement titer and urinary urobilinogen, urinary bilirubin, serum bilirubin, serum protein, serum colloidal reaction or the damage of excreting function. 10. The relative marked decline of complement titer was observed on the cases with the severe damage of liver parenchymal cells and the marked multiplication of intracellular tissue by the liver biopsy. 11. The decline of complement titer was observed on the most of cases with the identification of auto-livr antibody.