Surgical anti-reflux therapy appears to involve the muscles of the proximal gastric cardia and those of the lower esophageal sphincter. In an experimental canine reflux model, we injected sclerosant solution into the submucosa of the proximal gastric cardia, hypothesizing that the subsequent fibrotic reaction might exert an anti-reflux effect. Reflux was induced by atropine infusion, and the amount of reflux was quantitated by pH monitoring. Endoscopic sclerosis was effective in preventing reflux induced by high-dose atropine. Because the length and pressure of the lower esophageal sphincter were unaffected by endoscopic treatment, reflux prevention was possibly related to enhancement of the gastric component of the reflux barrier.