Venocclusive disease, a form of Budd-Chiari syndrome, was diagnosed in a 49-yr-old woman. The patient had portal hypertension associated with obliteration of the smaller hepatic venules. A liver biopsy specimen showed centrilobular necrosis and congestion. Analysis of food supplements the woman regularly consumed showed the presence of pyrrolizidine alkaloids. The major source was a powder purporting to contain ground comfrey root (Symphytum sp). We calculated that during the 6 mo before the woman was hospitalized, she had consumed a minimum of 85 mg of pyrrolizidine alkaloids (15 micrograms/kg body wt X day). The clinical and analytic findings were consistent with chronic pyrrolizidine intoxication, indicating that low-level, chronic exposure to such alkaloids can cause venocclusive disease.