The results of seven laboratory tests of liver function, including spleen/liver activity ratios obtained by densitometric analysis of scans, are analyzed in 50 patients with proven Laennec's cirrhosis. In this series, the liver scan not only disclosed the liver gross anatomy and structural abnormality and established the best possible site for biopsy examination, but also, the increased splenic activity served as a useful diagnostic indication of Laennec's cirrhosis. Of 50 proven cases of Laennec's cirrhosis, 41 (82%) had abnormal spleen/liver ratios. An abnormal spleen/liver ratio in combination with abnormal results from any one or two other tests was relatively effective in the detection of cirrhosis. The accuracy is improved if the other laboratory tests are chosen from among tests for serum albumin, serum bilirubin, and SGOT. (Liver abnormalities other than cirrhosis can also present an abnormal spleen/liver ratio.) This simple determination extends the value of the liver scan commonly requested in search of metastases, primary lesions, or inflammatory processes, or in preparation for needle biopsy examination.