We have performed a side-to-side portacaval shunt as the treatment of choice in six cases of primary Budd-Chiari syndrome. All the patients (three men and three women, mean age 33 years) had marked hepatomegaly and massive ascites. Four patients had endoscopically proved esophageal varices with no episodes of bleeding. Preoperative angiographic studies, caval pressure measurement, laparoscopy, liver biopsy specimens, liver scanning, and liver function tests confirmed the diagnosis. A possible etiologic factor was evident in only two cases. A plain side-to-side portacaval shunt was performed in four patients, while two required the interposition of a graft. One patient died after surgery of hepatorenal syndrome. Four of the surviving patients are free of ascites and doing well at 29, 27, 25, and 6 months. The remaining patient subsequently developed cirrhosis and died 76 months after surgery. None of the patients who survived developed encephalopathy. Shunt patency was confirmed endoscopically by variceal decompression in the four patients with esophageal varices. We believe the side-to-side portacaval shunt is a reliable and effective procedure for the definitive management of primary budd-Chiari syndrome.