We report a case of granulomatous mastitis caused by Mycobacterium tuberculosis in an immunocompetent woman with chronic inflammatory lesions of the breast. It was diagnosed by detection of mycobacteria DNA using polymerase chain reaction technique targeting IS6110 insertion element of M. tuberculosis complex in a paraffin-embedded histological specimen. The primary breast tuberculosis is rare, even in countries where the incidence and prevalence of pulmonary and extra pulmonary tuberculosis are high. It should be suspected in female patients with chronic granulomatous mastitis with no apparent cause. The cornerstone of treatment is antituberculous chemotherapy, and surgery is rarely required http://dx.doi.org/10.7705/biomedica.v33i1.1426