Mycobacterium avium subsp. paratuberculosis (MAP) is a member of the Mycobacterium avium complex, and is the etiologic agent of Johne's disease (paratuberculosis) in a wide variety of animal species. Animals with clinical signs of paratuberculosis and asymptomatic carriers spread the agent by their milk, feces and sperm. While milk may carry the microoganism, indirect contamination may also caused by feces. As well as milk, cheese, yoghurt, cream, butter, ice cream and other dairy products can also carry the pathogen. The increase in the incidence of Crohn's disease in humans and Johne’s disease in dairy cattle is observed worldwide. The detection methods of MAP in milk and dairy products are important to obtain reliable results in interpreting the role of food and possible relationships between these diseases with their high clinical and pathological similarities. For this purpose, MAP agents can be investigated by classical cultural and direct diagnosis methods such as Ziehl-Neelsen staining, fluorescence microscopy, solid-phase cytometry and bioluminescence in milk and dairy products. In addition to these methods, serological techniques such as radioimmunoassays-RIA, enzyme-linked immunoassays-ELISA, agar gel immunodiffusion assay-AGID and complement fixation-CF test and molecular techniques such as polymerase chain reaction-PCR, nucleic acid hybridization, immunomagnetic separation PCR, Nested PCR, Real-Time PCR or the rapid methods which are the combination of these techniques have also been developed.