In May 1983, a surveillance system was set up at a rural diarrhoea treatment centre of the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) to study a 20% systematic sample of all admissions. Between May 1983 and April 1984, 2,635 patients were studied. A recognized enteric pathogen was detected in 69% of the patients screened, 15% of whom had a mixed infection. Vibrio cholerae 0: 1 was the most common enteropathogen detected (39%), followed by enterotoxigenic Escherichia coli (ETEC) (14%), Shigella spp. (11%), and Campylobacter jejuni (11%). Detection of C. jejuni was highest in infants, Shigella spp. in children between 1-4 years and V. cholerae 0:1 in children between 3-9 years of age. 75% of patients presented with watery diarrhoea, a presentation that was significantly more common in patients infected with V. cholerae 0:1 (94%) and ETEC (88%). Bloody diarrhoea was the presenting complaint in 18% of all patients, but in 65% of patients in whom Shigella spp. was isolated. Although 91% of patients reported that they had prior experience of use of oral rehydration therapy (ORT), 54% of the patients came to the treatment centre with no or mild dehydration and more than half of them did not use ORT before coming to the treatment centre. Most of these patients could have been safely treated at home if ORT could be made available and acceptable.