Endoscopic balloon dilation is becoming an effective alternative to surgery to treat patients with benign pyloric stenosis. We have encountered a 64-year-old woman with pyloric stenosis from earlier peptic ulcer disease. Due to concerns regarding her existing cardiac dysfunction, through-the-scope balloon dilation was performed as opposed to open surgery. The patient's condition was subsequently complicated by pneumoperitoneum, pneumomediastinum and subcutaneous emphysema. A perforation of gastrointestinal tract was considered. She underwent repair and reconstruction for the duodenal laceration and later recovered uneventfully.