A distal gastrectomy reconstruction using the Billroth II procedure was performed for epigastralgia and liver dysfunction caused by a duodenal anomaly in an adult. Hypotonic duodenography revealed the duodenum to be obliterated at the junction of the second and third portion, while the third portion was joined to the first portion. Endoscopic retrograde cholangiopancreaticography (ERCP) and ultrasonography showed a normal construction of the common bile and pancreatic ducts, as well as gallstones. To prevent ingested food from the stomach from entering the obliterated second portion, a distal gastrectomy (Billroth II) was thus performed. The patient has remained asymptomatic for 4 years since surgery. A distal gastrectomy reconstructed by a gastrojejunostomy is thus considered to be an effective method for improving the symptoms caused by food stasis in the obliterated second portion of the duodenum.