The benzo-pyrones reduce all high-protein oedemas, including lymphoedema and elephantiasis, by increasing the numbers of macrophages and their normal proteolysis. Thus they remove the excess protein, and thereby the oedema which is caused by it. They also remove the stimulus it provides for chronic inflammation and fibrosis, and its action as a culture medium for bacteria. Coumarin (5,6 benzo-[alpha]-pyrone, 56 BaP) and oxerutins (HR, O(beta-hydroxy-ethyl)-rutosides) have been used in many clinical trials on a variety of high-protein oedemas. Four such trials are summarised here: on lymphoedema and elephantiasis (from many causes in Australia, and filaritic in India and China). The drugs reduced these much more slowly than adequate physical therapy, but they did reduce them. About half the excess volume was removed over six months in the Australian trials. In India and China similar rates were achieved with lymphoedema, but elephantiasis reduced at a slower rate. The benzo-pyrones convert a slowly worsening condition into a slowly improving one. No compression garments are necessary. In addition, the drugs considerably reduce the number of attacks of secondary acute infection, reduce the deformities of elephantiasis and considerably improve the patients' comfort and mobility. They may be taken orally, or applied topically, have very low toxicities and only few, minor side-effects. They are useful in many other forms of high-protein oedema, and improve the results of physical therapy for lymphoedema.