The unexpected observation of severe pulmonary tuberculosis after a 7-month combined pegylated interferon-ribavirin for chronic hepatitis C, prompted us to search an eventual immunodeficiency (lymphopenia and/or depletion of CD4+ T-lymphocytes. The retrieval of a chest radiograph incidentally performed 11 y before and showing a probable primary tuberculosis, paralleled a negligible clinical history. The enlargement of interferon indications needs careful evaluation for prior (usually missed) tuberculosis, to prevent or avoid its possible reactivation. Latent tuberculosis is increasingly reported because of extended life expectancy, immigration, and recent availability of cure for multiple chronic disorders, which are often borne by primary-secondary immunodeficiency.