Investigations on the entry of lymphocytes into lymphatic organs and the infectious areas are limited. The HEVs which organize the entrance of lymphocytes into immune system are located at the paracortical area of the lymph node. HEVs differ from blood vessels by their ultrastructure and enzymatic properties of their endothelial cells. In present review, HEVs were compared with the other blood vessels. Migration of lymphocytes were discussed.