The clinical and biochemical evolution of hepatic lesions in 124 patients with toxic oil syndrome from 1981 to 1986 has been reviewed. Most patients became asymptomatic during the early phase of the disease and abnormal liver function tests gradually normalized. In 1981, liver injury resembled drug-induced cholestatic hepatitis in 31 patients, and in 1 patient chronic destructive nonsuppurative cholangitis was evident. From 1982 to 1986 serial liver biopsies demonstrated toxic cholestatic hepatitis in 14 patients, chronic active hepatitis in 13, and nonalcoholic cirrhosis in 4. Nineteen patients showed lesions suggestive of alcoholic liver disease, but only 8 had a history of heavy alcohol intake. One patient developed biliary cirrhosis, another liver cell adenoma, and 8 nodular regenerative hyperplasia of the liver. We conclude that although liver injury had subsided in most patients, a significant number developed a variety of different liver diseases after follow-up for 5 yr.