The hypertensive lower esophageal sphincter (HLES) is a disorder of esophageal motility associated with dysphagia and chest pain. Although well characterized manometrically, opinions differ greatly with regard to its pathophysiology and its management. Therapy is limited to a few medications, esophageal dilatation, and even surgery, although none of these options are consistently successful. In this case report we describe a 54-year-old woman with HLES and dysphagia who was successfully treated with botulinum toxin injection of the lower esophageal sphincter (LES). Esophageal manometry after botulinum toxin therapy revealed normalization of LES pressures. Three months after therapy, symptoms returned and repeat esophageal manometry demonstrated the return of elevated LES pressures. This report is the only published case of botulinum toxin injection into the LES with both pre- and post-treatment esophageal manometric data. This case report is evidence that LES dysfunction produces symptoms in patients with HLES, and that reduction in LES pressure improves symptoms. Current pathophysiologic hypotheses for HLES-associated dysphagia and its treatment are briefly reviewed in this report.