A new contrast agent has been developed for the opacification of the esophageal lumen in Magnetic Resonance (MR) Imaging. The contrast agent consists of an emulsion of low-density and high-viscosity barium paste employed for the CT study of the esophagus (E.Z.E.M., Westbury, USA) and a small amount of Gadolinium-DTPA (Magnevist, Schering, Germany), diluted in 3 ml of saline solution. In vitro evaluation of the contrast solution showed high-signal intensity on T1-weighted SE sequences. The study was subsequently performed on 5 healthy volunteers and 30 subjects with clinical indication for MR Imaging of the chest. The complete opacification of the esophagus was obtained in 12 of the 16 patients (75%) who presented no pathological involvement of the esophagus. The esophageal lumen was completely opacified in 8 patients with esophageal carcinoma and in 1 case of esophageal leiomyoma. In the cases with esophageal carcinoma, lumen opacification allowed the evaluation of tumor growth (concentric or eccentric), a more detailed definition of tumor extent, with assessment of neoplastic wall thickening, and the evaluation of the possible infiltration of adjacent organs. Lumen opacification was obtained in 8 of 10 patients (80%) affected with other chest conditions secondarily involving the esophagus. In these cases, lumen opacification helped to localize the esophagus and to evaluate its involvement by adjacent tumors.