Achalasia and gastroesophageal reflux disease (GERD) represent diverse physiologic disorders both of which result from lower esophageal sphincter (LES) dysfunction. Fortunately, both diseases are benign and amenable to surgically corrective therapies. Achalasia is characterized by destruction of the smooth muscle ganglion cells of the myenteric plexus (Auerbach) resulting in motor dysfunction, incomplete LES relaxation, and progressive esophageal dilation. GERD is frequently characterized by hypotonia or shortening of the LES. Local anatomical derangements such as a hiatal hernia (eg, sliding type I hernia) can predispose to GERD. Other predisposing factors for GERD include obesity, smoking, alcohol, and pregnancy. Transient LES relaxation is the most significant factor in the development of GERD. Transient LES relaxations last from 10 to 45 seconds and are not related to swallowing. The diagnostic workup of achalasia and GERD may include barium esophagram, upper gastrointestinal endoscopy, pH monitoring, and esophageal manometry. The different medical treatment options for achalasia comprise pharmacologic treatment, botulinum toxin, and balloon dilation. Surgical interventions include Heller myotomy, which is usually combined with a partial fundoplication. GERD is managed by treating the predisposing factors, using medications (ie, anatacids or proton pump inhibitors) and surgery (ie, fundoplication). Recently, endoluminal therapy has been employed in the treatment of GERD with promising short-term results.