In 58 previously well-nourished patients who were fed cow's milk and who later developed persistent diarrhoea (≥15 days), data obtained during the first 8 days of acute diarrhoea were compared with those of patients whose episodes lasted ≤8 days. Children with persistent diarrhoea weighed less at birth, passed ≥6 stools/day during the first 48 hours, received early treatment with antibiotics. Their milk feedings were stopped during the first 48 hours, they had a past history of digestive diseases and hospitalizations, they were brought in for consultation after 5 days of symptoms and their nutritional status deteriorated more (p<0.003, p<0.03, p<0.0001, p<0.0001, p<0.0001, p<0.002, p<0.0001, and p<0.03, respectively). Their mothers were significantly younger (p<0.0013), had better schooling (p<0.037), and fewer children (p<0.044), and were separated from the index child during the day more often (p<0.056). After persistent diarrhoea was diagnosed, enteropathogens in stools or lactose i