Paratuberculosis is a chronic enteritis that affects ruminants and is caused by Mycobacterium avium paratuberculosis (Map). The disease is worldwide spread and causes important economic losses. In Brazil, the bacillus was isolated in the south and northeast regions of the country and in Rio de Janeiro, but there are no enough epidemiological studies about its occurrence. Isolation of Map from tissues or fecal samples is 100% specific, but Map shows the most fastidious growth of all mycobacteria. Incubation lasts 8 -12 weeks, with a dependency on exogenous mycobactin J. Diagnostic tests based on specific DNA sequences allow fast and secure identification, and PCR has been used to confirm positive culture results and to identify Map in feces, milk and tissues. The most frequently used target sequences are the gene encoding the 16S rRNA, and the insertion element IS900. Serological assays are widely used for the herd diagnosis of the disease. A commercial ELISA with M. phlei pre-adsorption step achieves a specificity of 95.4% to 99% and a sensitivity of about 45%. Until now, there is no effective treatment for ill animals and control programs are based on managing procedures of herds and culling of symptomatic animals. In Brazil, paratuberculosis was recently identified and has been demonstrated even in autochthonous closed herds. Therefore, it is essential to perform an epidemiological national research and to investigate the economic impact of the disease in our herds. These results could promote a control program of paratuberculosis adapted to the Brazilian requirements.