The dependence of pathomorphological changes in the regional lymphatic ganglia of the dog's kidney upon the duration of experimental hydronephrosis is shown. The development of necrosis in some of them points out indirectly to the participation of the renal lymphatic system in carrying off the urine saturated with toxic products persisting in it for a long period. Increased dilatation of intermediate and medullary sinuses is connected with continuous inflow of the lymph that contributes to its congestion and then leads to the retrograde flow. A mechanical obstraction appears on the way of lymph and this fact aggravates mechanical insufficiency of the lymph circulation. At the same time this particular case is lymphogenic sclerosis, which is induced by acumulation of disturbed metabolism products in the intermediate tissue brought by the lymph.