The current concepts in persistent diarrhoea (PD) are reviewed. 102 patients with acute diarrhoea and 85 with PD are studied. All were less than one year old. Information about age, nutritional status, time of breast feeding, previous episodes of acute and persistent diarrhoea and the previous use of drugs is registered. Microbiological and parasitologics studies were done to identify enteric pathogens. To prove the association of PD and the exposure to different risk factors the statistic method of Chi square (chi 2) was used and the odds ratio (OR) estimated. In order of importance and according to the OR the risk factors identified were: previous episodes of PD, malnutrition, less than one month with breast feeding, the use of metronidazol and antibiotics, multiple infections, previous episodes of acute diarrhoea and the identification of enteric pathogens. The most frequent pathogen was Salmonella followed by entero pathogenic Escherichia coli.