We studied the relationship between the ratio of serum aspartate aminotransferase (ASAT) to alanine aminotransferase (ALAT) and histologic changes in human and experimental alcoholic liver disease. The patient population included 52 hospitalized patients enrolled in a Veterans Administration Cooperative study. The experimental animal group consisted of male Wistar rats fed an ethanol-liquid diet. Of the 52 patients with alcoholic hepatitis, 33 had evidence of cirrhosis. The mean +/- SD for the ASAT/ALAT ratio in the group with alcoholic hepatitis and no cirrhosis was 1.47 +/- 0.84, the mean +/- SD in the group with hepatitis and cirrhosis was significantly higher (2.68 +/- 1.32, p less than 0.01). There was no difference in the ratio between the rats with and without liver fibrosis. The cause for the increased ASAT/ALAT ratio in serum in the presence of cirrhosis is unknown and may reflect more severe liver damage.