Perforation of the small bowel during SWL is reported for the first time. The patient was treated in the prone position for a ureteral stone with 4500 shockwaves. There were no underlying or predisposing factors for the damage to the gut with the exception of the large number of shockwaves at a high energy setting. It is concluded that SWL in the prone position with shockwaves traversing the peritoneal cavity carries a risk of damage to the bowel. A reduction of the number of shockwaves and the energy level should be considered in this setting.