The efficacy of a group of anti-inflammatory drugs with similar modes of action was tested on thermal oedema. Of these, coumarin and sodiumrutin-sulphate were most effective. A combination of these, marketed as Venolot, although still beneficial, was not as effective as either given singly. The other drugs tested--levamisole, Reparil and Venoruton--although also of some benefit in treatment of this oedema, did not approach the overall effectiveness of coumarin of sodium-rutin-sulphate. Both drugs are characterized by a very wide safety margin between the therapeutic and the toxic dose. In addition, they are cheap, easy to obtain and can be taken orally. They work by stimulating phagocytosis, enzyme production and thus proteolysis and a subsequent removal of protein and oedema fluid from the injured tissues.