Volumetric comparisons of portions of liver and spleen were performed in patients with chronic liver diseases to determine their diagnostic value. Volumetric ratios of liver and spleen were determined by CT examination in 34 normal subjects and 125 consecutive patients with histologically proved liver cirrhosis, chronic active hepatitis, chronic persistent hepatitis, acute hepatitis, or fatty liver. Ratios of caudate lobe, spleen, and lateral segment of the left lobe of the liver to the remainder of the liver, right lobe and medial segment of the left lobe (RL+LM), were calculated. The product of caudate lobe/RL+LM and spleen/RL+LM was of value in differentiating liver cirrhosis from other liver disease, with a sensitivity of 60%, specificity of 98%, and accuracy of 86%. The same ratios differentiated liver cirrhosis and chronic active hepatitis from other liver diseases with a sensitivity of 79%, specificity of 100%, and accuracy of 90%. Volumetric ratio measurements are useful in the diagnosis of cirrhosis and chronic active hepatitis.