Non-peptic, nonhypertrophic pyloric stenosis has rarely been reported in pediatric literature. Endoscopic pyloric balloon dilation has been shown to be a safe procedure in treating gastric outlet obstruction in older children and adults. Partial gastric outlet obstruction (GOO) was diagnosed in an infant by history and confirmed by anupper gastrointestinal series (UGI). Abdominal ultrasonography and computed tomography scan excluded idiopathic hypertrophic pyloric stenosis, abdominal tumors, gastrointestinal and hepato-biliary-pancreatic anomalies. Endoscopic findings showed a pinhole-sized pylorus and did not indicate peptic ulcer disease, Helicobacter pylori infection, antral web, or eviden-ce of allergic and inflammatory bowel diseases. Three sessions of a step-wise endoscopic pyloric balloon dilation were conducted under general anesthesia and a fluoroscopy at two week intervals using catheter balloons (Boston Scientific Microvasive?, MA, USA) of increasing diameters. Repeat UGI after the first session revealed normal gastrointestinal transit and no intestinalobstruction. The patient tolerated solid food without any gastrointestinal symptoms since the first session. The endoscope was able to be passed through the pylorus after the last session. Although the etiology of GOO in this infant is unclear (proposed mechanisms are herein discussed), endoscopic pyloric balloon dilation was a safe procedure for treating this young infant with non-peptic, non-hypertrophic pyloric stenosis and should be considered as an initial approach before pyloroplasty in such presentations. Non-peptic, nonhypertrophic pyloric stenosis has rarely been reported in pediatric literature. Endoscopic pyloric balloon dilation has been shown to be a safe procedure in treating gastric outlet obstruction in older children and adults. Partial gastric outlet obstruction (GOO) was diagnosed in an infant by history and confirmed by anupper gastrointestinal series (UGI). Abdominal ultrasonography and computed tomography scan excluded idiopathic hypertrophic pyloric stenosis, abdominal tumors, gastrointestinal and hepato-biliary-pancreatic anomalies. Endoscopic findings showed a pinhole-sized pylorus and did not indicate peptic ulcer disease, Helicobacter pylori infection, antral web, or eviden-ce of allergic and inflammatory bowel diseases. Three sessions of a step-wise endoscopic pyloric balloon dilation were conducted under general anesthesia and a fluoroscopy at two week intervals using catheter balloons (Boston Scientific Microvasive ?, MA, USA) of increasing diameters. Repeat UGI af The first session revealed normal gastrointestinal transit and no intestinalobstruction. The patient tolerated solid food without any gastrointestinal symptoms since the first session. The endoscope able to be passed through the pylorus after the last session. Although the etiology of GOO in this infant is unclear (proposed mechanisms are herein discussed), endoscopic pyloric balloon dilation was a safe procedure for treating this young infant with non-peptic, non-hypertrophic pyloric stenosis and should be considered as an initial approach before pyloroplasty in such presentations.