ALTHOUGH Courtice1 had previously demonstrated the significance of the lymphatic circulation in portal venous hemodynamics, it was not until 1960 that Dumont and Mulholland2 first reported that lymph flow rates and pressures in the thoracic duct were markedly elevated in patients with cirrhosis and portal hypertension. In 1962, they introduced the concept of thoracic duct cannulation in the treatment of bleeding esophageal varices.3 Since then, Bowers et al4 and Naso and Munna5 have reported varying degrees of success with the procedure in the preshunt management of bleeding from esophageal varices. After brief clinical experience with this procedure, we undertook the following experiments in an attempt to study the role of thoracic duct cannulation in dogs with surgically created ascites and portal hypertension. Healthy adult mongrel dogs weighing between 12 and 16 kg (26.4 and 35.3 lb) were used in this study. All dogs received rabies