Blood serum alkaline phosphatase (AP) level was found elevated in the patients suffering from eczema, neurodermatitis, eczema with large skin sites involved, and in those with trophic ulcers of various origins, as against normal subjects and reference patients with sarcoidosis and Kaposi's sarcoma. Elevated level of the enzyme activity is directly related to exacerbation stage and size of the skin site involved; this level reduced after therapy and this reduction was associated with clinical improvement. No concomitant visceral abnormalities (calculous cholecystitis, liver cirrhosis, or malignant tumors) were detected in the examinees, that might influence the blood serum AP activity.