ABSTRACT. A simple method of lymphography of the thoracic duct was investigated. Using three female beagles, contrast media were administered rectally, vaginally and into the perianal tissue. The administration sites were gently massaged, and imaging was carried out at constant intervals using computed tomography and radiograph. Moreover, Indian ink was administered into the rectum mucous membrane in dogs for proof of this method of lymphography, and the lymph drainage routes were observed. The investigation showed that clear computed tomography and radiographic contrast images of the thoracic duct were obtained by subcutaneous and submucosa injection of angiography contrast medium and 3D processing of these images revealed the three-dimensional positions and course of the thoracic duct and cisterna chyli. Chylothorax is a condition in which chyle leaks into the thoracic cavity and accumulates. Symptoms include respiratory impairment, weight loss and exercise intolerance. In most cases, the etiology is unknown [4]. A number of medical and surgical treatments are currently suggested for the treatment of chylothorax. In many cases, because medical therapies are unable to resolve chylothorax completely, surgical treatment must ultimately be considered. To date, surgical treatment of chylothorax has included thoracic duct ligation [2], pleuroperitoneal shunting [11], thoracic omentalization [8], cisterna chyli ablation [6] and pericardiectomy [5], either alone or in combination with thoracic duct ligation. Thoracic duct ligation is recommended as the 1st choice among these methods [3,5]. One possible cause for the failure of thoracic duct ligation and subsequent recurrence is the occurrence mistakes in the surgery itself, such as failure to tie all of the complex tributaries into which the thoracic duct divides [1]. The thoracic duct in dogs is known to form either a single duct or multiple tributaries within the thoracic cavity after passing through the aortic hiatus, and their courses also display a complex morphology [7]. The position and course of the thoracic duct and cisterna chyli must be confirmed preoperatively when thoracic duct ligation or cisterna chyli ablation is performed, for which lymphography of the thoracic duct is of course required [1]. Current methods for performing lymphography of the thoracic duct involve the injection of contrast medium into the mesenteric lymph nodes during laparotomy under anesthesia or contrast imaging of the thoracic duct after the injection of contrast medium into the popliteal lymph node of a pelvic limb [2, 9, 10]. However, laparotomy is an invasive procedure, and reliable results cannot be obtained by percutaneous penetration of lymph nodes when the size and position of these lymph nodes are undetermined. In the present study, beagles were used to investigate new simple sites for administration of contrast media and for obtaining lymphographic images by computed tomography (CT) or radiography of the thoracic duct, which will have clinical applicability.Three healthy ...