The different clinical features of venous leg ulcers have different etiology and pathogenesis, and therefore require different therapy. One should distinguish between ulcerations with origin in the external or internal fascia; also between periphlebitic, engirdling, "blow-out", hypodermitic and siderosclerotic ulcers, and between ulcers due to erosion or venous stasis. The differentiation into leg ulcers caused by rheumatoid disease, hematological disorders and organic diseases of large and small vessels is of importance for the proper treatment.