Bacteriological studies were carried out on approximately 10% of the infants of a poor urban population in Manaus - Amazonas. One third of the infants had diarrhoea at the time of faeces collection. One strain of Shigella sonnei and five different serogroups of enteropathogenic E. coli were isolated from the faeces of the infants with diarrhoea. Three strains of Salmonella sp. and five different serogroups of pathogenic E. coli were isolated in the faeces of infants without diarrhoea. The strains of Shigella sonnei and pathogenic E. coli showed multiple resistance to antimicrobial drugs.