Fifty patients with ulcerative colitis, 24 with Crohn's disease, and 50 controls were studied by liver function tests and abdominal ultrasound scan. Twenty-two percent of ulcerative colitis patients, 29% of Crohn's disease patients, and none of the controls showed abnormal liver function tests. All subjects with abnormal liver function tests also had changes in ultrasound liver scan, consisting of hepatomegaly and/or a dysechoic liver echo pattern. Furthermore, the same ultrasound changes were observed, in the absence of any liver function test abnormalities, in 58% of ulcerative colitis patients, 50% of Crohn's disease patients and 6% of controls (P less than 0.0005, inflammatory bowel disease versus controls). Overall, some evidence of liver involvement, as judged by abnormal liver tests and/or abnormal ultrasound liver scan, was detected in about 80% of inflammatory bowel disease patients. Six patients with minor abnormalities of liver function tests underwent liver biopsy and 5 of them had pericholangitis. Ultrasound liver scan may provide a useful tool to evaluate the occurrence of liver involvement in inflammatory bowel disease patients.