Biliary endoscopic sphincterotomy (ES) followed by biliary orifice dilation (BOD) with large-diameter balloons (> 12 mm) is a relative new technique for extraction of large biliary stones. However, the safety and the potential complications of this combined technique are not known yet. We present a patient who developed benign retroperitoneum after ES plus BOD with large-diameter balloon for removal of a large biliary stone, which was successfully treated conservatively. To the best of our knowledge this is the first report of such a complication after introduction of this method to clinical practice.