Liver and spleen size were measured in 11 normal subjects and 12 patients with cirrhosis. Volume was calculated by adding together the area measurements obtained from successive transverse abdominal scans. The normal mean volume of the liver (+/- S.D.) was 1,493 +/- 230 cm3 and that of the spleen was 219 +/- 76 cm3; interobserver variability was 4-8% and the day-to-day coefficient of variation was 6-10%. In cirrhotic patients studied prior to and 7-10 days after a distal splenorenal shunt, the mean liver volume fell from 1,642 to 1,529 cm3 (p less than 0.06) and the mean spleen volume from 660 to 507 cm3 (p less than 0.006), supporting the use of such a shunt in selective decompression of varices and maintenance of portal hypertension. This is a clinically useful method of measuring organ volume with the required sensitivity.