A 44-year-old woman was admitted from the emergency department with severe acute upper abdominal pain. The patient had undergone a laparoscopic Roux-en-Y gastric bypass (RYGBP) operation 16 months previously. CT scan showed intraabdominal free air. At emergency laparoscopic reoperation, a perforated ulcer at the gastrojejunostomy was found. This late complication of RYGBP can be a rapidly progressing life-threatening situation, and requires prompt treatment. Closure and omental patch were successful laparoscopically.