Histomorphologic changes of the lymphatic system of the liver and thoracic duct were examined. e diameters of lymphatic segments isolated from the thoracic ducts of ascitic and normal broilers at 32 to 37 days of age were measured using an optical micrometer measurement system. e histopathological picture of the segments of lymphatic tissue showed lymphatic cysts bilaterally along the posterior vena cava. e hepatic capsule manifested edema, thickening, and cellular proliferation. Microscopic changes in lymphatic vessels of the hepatic capsule include lymph embolism, and lymphatic plasma retention in lymphatic cysts. In some cases, distended lymphatic vessels exhibited protuberances, and lymph leaked from the lymphatic cysts into the surrounding swollen and degenerated endothelial cells of the thoracic duct. Sometimes, extensive endothelial cell loss was observed, and their exfoliated fragments were also seen. Marked dilatation of thoracic duct and lymph embolism, leaking of lymph, edema in some fibers and the enlargement of spaces between fibers, swollen intimas, and rupture and bleeding of the thoracic duct were also visible. e thoracic duct's long and short semi-axis, and the cross sectional area of the thoracic duct differed significantly between normal and ascitic broilers.