Diarrhoea up till now is still a major problem in Southeast Asia with high morbidity and mortality, particularly among children under 5 years of age, with the peak in children between 6 - 24 months. In Indonesia, in 1981, it was estimated that there are 60 million episodes with 300,000 - 500,000 deaths. In the Philippines, diarrhoea ranks as a second cause of morbidity (600 per 100,000 in 1974) and second cause of infant mortality (5 per 1,000 in 1974). In Thailand, in 1980, the morbidity rate was 524 per 100,000 and the mortality rate 14 per 100,000. In Malaysia, in 1976, diarrhoea was still ranking number 5 (3.1%) as a cause of total admission and number 9 (2.2%) as a cause of total deaths. In Singapore, diarrhoea still ranks number 3 as a cause of deaths (4% of total deaths). In Bangladesh, the overall attack rates imply a prevalence of 2.0% for the entire population, with the highest for under 5 groups i.e. 4.1%. The diarrhoea episode in rural population is 85.4%, 39% of them are children under 5. The most common enteropathogens found in all countries are rotavirus followed by Enterotoxigenic E. coli, Vibrio spp., Salmonella spp., Shigella spp. and Campylobacter. Malnutrition and decline of giving breast-feeding play an important role in causing high morbidity, besides socio-economic, socio-cultural and poor environmental sanitation.