In a patient with cirrhosis and bleeding esophageal varices who had previously undergone a partial gastric resection, the gastric balloon of a Sengstaken-Blakemore tube was inadvertently placed into the efferent jejunal limb of the gastrojejunostomy. Inflation of the balloon to the standard volume of 150 ml resulted in rupture of the jejunum. Precautions in the use of the Sengstaken-Blakemore tube that might prevent this complication are described.