Up to the present time, no simple method has existed for gauging the true size of an oesophageal tumour. The intimate relations between the azygos vein and the oesophagus in the thorax between D3 and D8 justifies this new study: azygography. On the basis of 40 examinations, 13 of which were followed by surgery in patients suffering from carcinoma of the oesophagus, as was indicated by classical anatomical data, azygography made possible the evaluation of tumour extension in the mediastinum and the involvement of adjacent structures, such as the right pulmonary artery. Azygography thus aided in the precision of surgical indications and in the delineation of the volume to be irradiated. The examination is carried out by selective opacification after catheterisation via the femoral vein. Radiological findings distinguish involvement by deviation, compression, invasion, obstruction and collateral circulation. In certain cases a part of the tumour itself is opacifield by vessels with an anarchic pattern. Comparison of the results of radiological study with surgical findings shows that the examination makes it possible to predict, between the level of the third and eighth thoracic vertebrae, difficulties in or impossibility of dissection of the tumour as well as, in the case of involvement of the arch, the necessity for total oesophagectomy with additional cervical approach. The accuracy of the information obtained is certainly less valuable as far as the lower third is concerned. Non-traumatic, simple and rapid, azygography would appear to be the examination of choice in defining the exent of a tumour of the middle third of the oesophagus, as a complement to clinical findings and barium swallow, being particularly valuable in determining the volume to be irradiated or on a pre-operative assessment.