Extraspinal tuberculous arthritis is a rare entity in developed countries, mostly found in populations of migrants. We describe a case of foot osteoarthritis in a young migrant, with an arduous diagnostic process. The sequence of the diagnostic studies (imaging, articular tap, bone biopsy together with cultures and molecular biology) must follow a logic based on clinical suspicion and on the knowledge of the diagnostic values of different tests. The diagnosis of tuberculous arthritis, a slowly progressing infection with a low bacteriologic burden, is difficult. The reported case emphases the need for perseverance. It shows the value of diagnostic procedures, their limits and the need for their integration to the clinical judgement.