Adverse effects of zidovudine, which mainly result in myopathies and hematological disorders, could be due to multitissular mitochondrial toxicity of the drug. During zidovudine treatment, most cases of lactic acidosis have been attributed to mitochondrial myopathy. We report a case of hepatocellular failure with lactic acidosis in a 33 year-old patient with the human immunodeficiency virus infection and treated with zidovudine for 8 months. Liver biopsy showed massive macrovacuolar steatosis and ultrastructural mitochondrial abnormalities similar to those previously described in the skeletal muscle. This is the second reported case of lactic acidosis and hepatocellular failure which is probably related to hepatic mitochondrial dysfunction caused by zidovudine.