Sandifer syndrome designates abnormal posturing in patients with gastroesophageal reflux. To explore its mechanisms via examining relationships among Sandifer syndrome posturing, abdominal wall contractions, and reflux episodes, we studied an affected child in detail. The study utilized esophageal pHmetry, surface electromyography, and split-screen videography. The multichannel physiologic study demonstrated association of rectus abdominis contraction with onset of reflux episodes (P < 0.001) and association of reflux episodes with Sandifer syndrome posturing. This child's subsequent course confirmed his diagnosis and suggested mechanisms of the association of reflux and Sandifer syndrome. We conclude that abdominal wall contractions may induce reflux episodes. Sandifer syndrome may be due to gastroesophageal reflux even without hiatal hernia, macroscopic esophagitis, or reflux symptoms. Despite the absence of more typical reflux symptoms and failure to respond to very aggressive medical therapy, Sandifer syndrome may resolve after fundoplication.