Definitive diagnosis of tuberculous pericarditis requires identification of bacilli in pericardial fluid or tissue. Conventional diagnostic methods are time-consuming and have a low sensitivity making bacteriological confirmation of the disease very difficult. Hereby, we report the case of molecular detection of Mycobacterium tuberculosis in pericardial fluid, bone marrow and peripheral blood from a 63-year-old woman with pericardial tuberculosis, using a nested PCR assay specific for IS6110 insertion element of M. tuberculosis complex. The patient had an excellent response to a three-drug combination anti-tuberculous regimen and 1 year later was asymptomatic, without evidence of constrictive pericarditis.