2. General Plan; The situation was reviewed in open forum by malaria experts from Cambodia, Thailand, and WHO, and was considered sufficiently worrying to prompt planning of an urgent investigation under the aegis of the Mekong Malaria Programme. First it is necessary to determine the level of in-vivo and in-vitro susceptibility to artemisinin derivatives. This will involve detailed clinical and laboratory studies associated with simultaneous assessment in-vitro in several laboratories including - A. National Malaria Control Programme, Pnomh Penh B. Mahidol Oxford Research Unit (MORU), Bangkok. C. Institut Pasteur, Pnomh Penh. D. Family Health International, Asia-Pacific Regional Office