Enteropathogenic Escherichia coli. (EPEC) are gram negative bacteria of great importance in the etiology of diarrhea in children under two years of age living in developing countries. It was first reported in 1946. Its pathogenic mechanism was unknown until 1970 when several papers were published in the attempt to find out their physiophatologic mechanism. These bacteria interfere on the small bowel resulting in parcial or sub total villous atrophy. This injury will revert when the infection subsides.