Inclusion Criteria:

• Subjects identifying their main symptom as a burning feeling in the mid epigastric area and/or chest area (ie, heartburn).
• Subject has a history of episodes of heartburn for 6 months or longer prior to Screening.
• Subject must have a history of episodes of heartburn for 4 or more days during the 7 days prior to Day -1.

Exclusion Criteria:

• Endoscopic Barrett's esophagus and/or definite dysplastic changes. History of dilatation of esophageal strictures.
• Subjects with erosive esophagitis (EE) as shown by endoscopy.
• Evidence of uncontrolled systemic disease. Co-existing diseases affecting the esophagus. Current or history of Zollinger-Ellison syndrome.
• Subject has abnormal laboratory values.
• Subjects with active gastric or duodenal ulcers within 4 weeks of the first dose.
• Subject known to have acquired immunodeficiency syndrome (AIDS).
• Known hypersensitivity to any proton pump inhibitor (PPI), any component of Dexlansoprazole MR, or antacid.
• Use of prescription or non-prescription PPIs, histamine (H2) receptor antagonists, or sucralfate.
• Chronic (>12 doses per month) use of nonsteroidal anti-inflammatory drugs (NSAIDs) or cyclo-oxygenase-2 (COX-2) inhibitors.
• Use of antacids (except for study-supplied Gelusil® ).
• Use of drugs with significant anticholinergic effects.
• Subjects who cannot discontinue the use of misoprostol or prokinetics
• Need for continuous anticoagulant therapy.
• Females who are pregnant or lactating.
• History of gastrointestinal surgery except for simple oversew of ulcer.
• History of cancer within 3 years prior to screening.
• Subject has participated in a previous Dexlansoprazole study.
• Subjects who, in the opinion of the investigator, are unable to comply with the requirements of the study or are unsuitable for any reason.