The inguinal lymph nodes of patients with primary lymphedema of lower extremities were investigated by light microscopy. It was found that sclerotization of regional lymph nodes can begin with both cortical and medullary parenchyma. Different stages of this process in lymph nodes were distinguished. These stages depend on the duration of the illness and the zone of organ where the first signs of sclerotization were observed. Small islands of lymphoid parenchyma were found in even well advanced sclerosis lymph nodes, and this allows to assume possibility of full regeneration of all structure of these organs when lymph circulation is normalized.