Hairy cell leukemia is a chronic B-cell lymphoid leukemia characterized by pancytopenia, splenomegaly, myelofibrosis and the presence in peripheral blood, bone marrow and spleen of atypical lymphoid cells with a hairy aspect and a particular immunophenotypic profil. The association HCL and tuberculosis has been established, but only few cases have been reported. We report a case of bone marrow tuberculosis with concomitant HCL. Initially, the histopathology of bone marrow led to a diagnosis of tuberculosis and myelofibrosis, without sufficient evidence for HCL. The anti-bacillary treatment was then started. Three months later, aspiration, biopsy and immunophenotyping of bone marrow were performed, a lymphoid population evoking hairy cells, was found. The patient received chemotherapy based pentostatin. The outcome was favorable.