History taking is the first step in the evaluation of a patient. An analysis of the information obtained provides the basis for the choice and order of diagnostic tests. In addition, it provides the clinician with the necessary information to determine the relevance of "abnormal tests" to the patient's problem. Dysphagia is a reliable symptom that indicates an abnormality in the swallowing mechanism. The history should contain a detailed description of the symptoms associated with dysphagia from the onset. Especially relevant are questions to determine if dysphagia is experienced every day or intermittently, with solid food or liquids or both, as well as presence and timing of associated symptoms such as, choking, coughing and regurgitation, changes in speech, heartburn and chest pain. It is clinically useful to divide swallowing into three phases: oral, pharyngeal and esophageal. Oral dysphagia is usually due to a neurologic disorder, decreased salivary flow or painful oropharyngeal lesions. Pharyngeal dysphagia is most frequently caused by neuromuscular disorders and less frequently by a Zenker's diverticulum, neoplasm or a mucosal web. Esophageal dysphagia is caused by a structural narrowing, such as produced by a peptic stricture, neoplasm or a Schatzki's ring or by a primary motility abnormality, such as achalasia or diffuse esophageal spasm or by motility abnormalities produced by inflammation caused by gastroesophageal reflux, medication-induced esophageal ulceration or infectious esophagitis.