Lymphatics, lymph and lymphoid cells are still considered to be different entities and not parts of one integrated system. Surgeons working on the problems of lymphedema study lymph flow kinetics but neglect lymph humoral and cellular constituents. Immunologists study the problems of lymph cells but neglect lymph transport and chemical composition. This article describes the author's own views on the function of the lymphatics, lymph proteins and cells as one integrated immunoregulatory system. Data from own studies on the peripheral lymphatic system performed mostly in man are quoted.