Population-based data on deaths due to diarrhoea among children less than 5 years of age were obtained from areas of Brazil (227 deaths), Senegal (531), Bangladesh (236) and India (146). Fatal episodes of diarrhoea were classified as either acute diarrhoea, dysentery, or persistent diarrhoea based on their duration and on the presence or absence of blood in the stools. Persistent diarrhoea accounted for over 60% of infant diarrhoeal deaths in Brazil, 47% in India, 36% in Senegal, and 26% in Bangladesh. In the latter two studies, over one-half of infant diarrhoeal deaths were due to acute watery episodes. Among children 1-4 years old dying from diarrhoea, persistent episodes were the most common in Senegal and India, whereas dysentery was the leading pattern in Bangladesh. These differences may be related to the use of oral rehydration therapy and the utilisation of health care, as well as to environmental characteristics, and are relevant for planning control strategies. Further data are required from other parts of the less developed world.