The epidemiological behavior of the intestinal inflammatory diseases (IBD) has varied in the last decades. In geographic areas of infrequent presentation, like Latin America, the rates of incidence and prevalence have had a frank increase.

It is presumed that this phenomenon it must to changes in environmental variables like the diet, the tobacco, the use of certain medicines, the appendectomy, stress and some styles of life. Etiology and pathogenesis of IBD are still unclear, although at the moment it is accepted that it is multifactorial. Between the implied factors they are: the environment, familiar factors, genetic factors and of the immune system.

In this review, we showed the epidemiological features of the IBD, with emphasis in the pediatric population. As well as the main environmental factors of risk, who are related to the IBD. We also mentioned s ome mechanisms and conditions as much inherited as acquired , that they have been involved in pathogenesis of the IBD

Keywords: Epidemiology, Pathogenesis, Etiology, Inflammatory Bowel Disease, Crohn Disease, Colitis Ulcerosa.

Abbreviations: Inflammatory Bowel Disease = (IBD).