We are far from being thoroughly acquainted with lympho-venous pathology, despite minute research in this field. The only physiological lympho-venous communications are macroscopic. The existence of microscopic communications has been proved in animals, but it seems that anastomoses become pathologically normal whenever the lymph flow is at all checked. It should be particularly noted that the vasculo-tissular equilibrium is precariously dependent on the physiological condition. The slightest disturbance can upset this balance, resulting in the formation of lympho-venous anastomoses, which attempt to set up a balance difficult to maintain.