The dorsal surface of the rabbit's ear is an easy place in which to produce a long-lasting lymphoedema, since the draining collecting lymphatics can readily be occluded. After six weeks of experimental lymphostasis the fine structure was examined and found to be identical with that observed elsewhere: The lymph capillary junctions were open here, as in some other regions where their support is not great. The benzopyrones produced their usual considerable reduction in the amounts of excess protein and oedema in the tissues. While they also reduced the concentration of protein in the lymphatics, they could not reduce their excessive dilatation, nor the increased numbers of open junctions, because the system was still occluded. After 32 weeks of experimental lymphostasis without benzopyrone therapy, much collagen was deposited and an increased number of macrophages present while protein concentrations were slightly reduced.