The organ-specific enzyme histidase was measured as an indicator of skin involvement in the blood of 52 patients with primary and secondary lymphedema of the upper and lower limbs. A stable type of the disease (degree I) was characterized by washing histidase off the derma into the blood. Mild and moderate histidase washing associated with skin dystrophy occurred with progression of the disease (stage II and III, respectively). In advanced lymphedema (degree 4) histidase does not enter blood from the skin. This fact is explained by total impairment of skin cell elements and their replacement for fibrous tissue. Both in primary and secondary lymphedema complicated by erysipelas histidase is washed off the dermocytes. The findings justify use of blood histidase indices for assessment of lymphedema patients' condition, formulation of indications for operation and concluding on the latter efficacy.