More than one billion diarrhoea episodes occur every year among children younger than 5 years of age in socioeconomically developing countries causing 2 to 2.5 million deaths. Information available from the 1980s to date suggests that the overall frequency of childhood diarrhoea has remained relatively constant, but with a steady decline of diarrhoea-assosiated deaths, mainly as a consequence of the introduction of Oral Rehydration Therapy (ORT). The interaction between malnutrition and intestinal infection is a leading cause of death in resource-poor countries. While ORT has resulted in an important fall in mortality related to acute diarrhoea, the syndrome of persistent diarrhoea and malnutrition continues to pose a major threat to the survival and health of children throughout the tropics. More than twenty viral, bacterial and parasitic enteropathogens are currently associated with acute diarrhoea. Rotavirus and Escherichia coli are the most common pathogens responsible for acute diarrhoea episodes in children. Infections caused by bacteria occur more commonly in areas with poor sanitation. The lack of appropriate sanitary conditions favors the existence of environmental contamination affecting children, especially infants, and leads to a high incidence of enteric infections. Other factors common to poverty, e.g severe malnutrition and decreased accessibility to medical care, increases the risk of death from diarrhoeal disease. Improvements in water quality and quantity, sanitation and hygiene, especially promotion of hand washing, are important aspects in preventing diarrhoea. Breastfeeding provides young infants with significant protection against morbidity and mortality due to diarrheal disease, and shoud be promoted in all areas of the world.