Technical Abstract: Mycobacterium paratuberculosis, the causative agent of Johne's disease in ruminant animals, has been linked as a causal agent of Crohn's disease in humans. Although similarities between Crohn's disease andJohne's disease do exist as both are chronic inflammatory disorders of the small intestine, there are distinct differences as well. The etiology of Crohn's disease is not well defined at this time despite rigorous efforts by researchers to identify a specific pathogen for this disease. Extensive studies have been conducted to isolate a viral or bacterial pathogen. Indeed, evidence todate does not prove that Crohn's disease is caused by either and may, in fact, be a multifactorial disorder. Regardless, it has become a concern for the dairy industry as consumer confidence has been influenced by reports that pasteurization may not destroy the bacterium. This paper discusses current evidence on viral and bacterial pathogens found in patients with Crohn's disease with an emphasis on mycobacteria. In addition, the paper reviews the current studies on heat inactivation via pasteurization of milk and the survival of M. paratuberculosis. These studies address consumer concerns about the safety of milk.