The bulletin reviews available information on biotic factors affecting sweet potato in eight countries in three important tropical production regions - south-east Asia, the Pacific, and east Africa. Information was obtained both from published reports, and directly from visits to key root and tuber-crop research institutions and discussions with many researchers in the Philippines, Indonesia, Thailand, Papua New Guinea, Uganda, Rwanda and Kenya. The most important diseases and pests are identified; the current status of sweet-potato research is reviewed; and specific recommendations are made for future research in these countries