This draft issue of the Reference Method for Marine Pollution Studies No. 43 was prepared in co-operation with the Food and Agriculture Organization of the United Nations (FAO) and the International Atomic Energy Agency (IAEA). It includes comments received from a number of scientists who reviewed the method and particularly the conclusions of the FA/UNEP Consultation meeting on the toxicity of selected substances to marine organisms held in Villefranche-sur-mer, France, 13-15 October, 1988.