The purpose is to assess the impact of compliance with measures of hygiene and water supply and oral rehydration on the diarrhoea with under 5 years of age in four villages of southern Côte d'Ivoire. The method used is to compare morbidity and mortality of children, firstly between two groups of villages without such measures, secondly in two villages before and after implementing them. Initially, an exhaustive survey has determined the incidence rate of diarrhoea, the proportion of deaths resulting from such diarrhoea as well as the mortality rate 1988. Two similar survey were made in 1990 and 1992. The results show a 50% reduction of the incidence rate of diarrhoea and a 85% reduction of the proportion of deaths related to diarrhoea in the villages with intervention. The mortality rate to diarrhoea was likewise reduced by 85%. These results show the importance of the improvement and accessibility to drinkable water and hygiene in the prevention of diarrhoea in areas children.