Bile peritonitis secondary to the rupture of choledochal cyst is an uncommon complication and has rarely been reported in adult patients. We report on an adult with a choledochal cyst who had an anomalous union of pancreaticobile duct presenting as a biloma due to spontaneous rupture. The fistula between choledochal cyst and biloma was closed after percutaneous drainage of the biloma. Resection of the choledochal cyst was performed after patient had been stabilized.