A combined clinico-morpho-physiologic investigation was conducted in 98 patients with primary and secondary lymphatic edema. All patients underwent lymphography by means of electron and light microscopy; biopsy specimens obtained from a lymphatic vessel at lymphography were investigated histologically, and contractility records were made. Pronounced disorders were demonstrated in the lymphatic vessels and their myocytes. New rational schedules of pathogenetic treatment for lymphedema of the lower limbs are outlined on the basis of the reported findings.