BACKGROUND: Esophageal impedance measurements are increasingly used to identify and quantify the presence of fluids in the esophagus. METHOD: A review of the available literature on clinical applications of impedance including combined impedance-manometry testing and combined impedance-pH monitoring is done. RESULTS: Combined impedance-manometry testing offers the opportunity to quantify esophageal bolus transit and clarifies the implications of esophageal motility abnormalities on esophageal function. This is of particular interest in patients with non-obstructive dysphagia and in patients with post-fundoplication dysphagia. Combined impedance-pH monitoring allows the detection of gastroesophageal reflux episodes independent of pH. This is of particular importance when evaluating patients with persistent symptoms on acid suppressive therapy. The ability to detect gastroesophageal reflux episodes with pH > 4 unfolds new questions on the optimal approach to patients with symptomatic non-acid reflux. CONCLUSIONS: Impedance technology allows the detection of fluid movements in the esophagus; further studies will determine the clinical utility of this new information.