Intramural duodenal hematoma is a rare complication of endoscopic biopsy. It is usually seen in children with growth failure and in patients with bleeding disorders or who are anticoagulated. It is frequently associated with acute pancreatitis. We present a case of an adult patient with Noonan's syndrome who developed postbiopsy intraduodenal hematoma. Abdominal ultrasound and computed tomography scan established the diagnosis. Conservative treatment was successful. According to a brief review of the literature, patients with Noonan's syndrome may develop hematoma after sampling of the duodenum because they present all the main predisposing factors. Additionally, pulmonic valve stenosis may be another predisposing factor, but this may warrant further investigation.