Poncet's disease is a reactive polyarthritis associated to active tuberculosis (TB), with excluded presence of mycobacterium in the joints and bones affected, and no other cause for the clinical arthritis. It is a frequently forgotten entity, especially in countries with low tuberculosis prevalence. It is described a case report of a man of Guinea-Bissau that presented symmetrical generalized polyarthralgias and hands swelling, clinical sacroiliítis and multiple enthesopathies. Serum and urinary biochemical testing were normal. Immunologic studies were negative and serum levels of angiotensin-converting enzyme and calcium were normal. Sexual transmitted diseases were excluded. The initial diagnose was undifferentiated polyarthritis or reactive arthritis. A persistent and refractory monoarthritis of the right wrist demanded a direct and cultural exam of the synovial fluid, synovial biopsy and protein chain reaction for TB that were negative. After he developed right wrist arthritis with purulent synovial fluid positive to TB in the direct exam and the detection of M. tuberculosis in the cultural exam. Granula was found in his chest radiograph. He was diagnosed a Poncet's disease reactive to a pulmonary TB infection.