The effects of lymphostasis and its treatment by a mixture of benzopyrones were studied in the pinnae of rabbit ears. The blood and lymph circulations to the dorsal surfaces of the ears were largely interrupted by excising a portion of skin down to the perichondrium from one edge to the other. The untreated ears became very lymphoedematous, became necrotic and tell off between 7 and 34 days after the operation. The treated ears were much less lymphoedematous, both to the naked eye and by electron microscopy. Owing to the ubiquity of action of the benzopyrones, the phagocytic capacity of the macrophages is enhanced, removing the accumulating protein, the metabolic products and thus the oedematous fluid. This improves the tissue oxygenation, encouraging lymphatic and vascular regeneration and, to a lesser degree, recanalisation. Also, the red blood cells are protected against lactacidotic rigidification and they and the macrophages are given an increased chance of survival in the remaining stagnant areas by the enhancement of glucose up-take and transport. Upon these factors rests the ability of the tissue to survive. The fact that the ears in the treated groups did not fall off, gives a real indication of the potentiality of the benzopyrones.