Enteropathogenic Escherichia coli (EPEC) remain an important world-wide cause of diarrhoeal disease and mortality of infants and young children. Research programmes around the world have, in recent times, made enormous strides towards a better understanding of EPEC pathogenesis, yielding unique insights into the molecular intercourse between host and pathogen. Recombinant DNA and cell biology techniques have provided powerful tools, giving the first intriguing glimpses of a wealth of bacterial products mediating complex host:pathogen interactions involving the subversion of normal host signalling processes. Much has been discovered since 1945, when E. coli was first implicated as a cause of diarrhoea. However, many questions remain unanswered and many more remain unasked. Much remains to be discovered, especially in the area of molecular interactions between host and pathogen and how they relate to the manifestation of disease in the patient.