The authors studied the immunological response before and after beginning anti-tuberculous therapy, of a previously health, HIV negative, 22 year old black male, from the Republic of Cape Verde. The patient had multiple vertebral bony lesions associated to subcutaneous abscesses. As immunological markers of antigen recognition, we measured blastogenic and cytotoxic responses and gamma-IFN secretion towards 30 kD, 65 kD, filtrate proteins of M. tuberculosis, M. tuberculosis (H37Rv) and PPD cultures. To characterise the role of cytokines during infection, expression of mRNA for gamma-IFN, IL-4 and IL-10 was also analysed. A slight increase of lymphocyte proliferation and gamma-IFN production was seen in response to purified protein derivative (PPD) and short term culture filtrate proteins (ST-CFP), after one month of therapy. More significant, was the increase in M. tuberculosis and PPD-specific cytolytic T lymphocyte response after one one month of treatment. After 6 months of treatment, blastogenic and cytotoxic responses and gamma-IFN production were considerably higher toward the antigen panel. The CD4/CD8 ratio increased from 0.7 to 1.4 after treatment. We observed that ST-CFP and MT-CFP induced increasingly higher lymphoproliferation and gamma-IFN production, confirming their role in the protective immune responses to M. tuberculosis. The reduced immune responses in the peripheral blood of this patient probably reflect a high activity in the local sites of infection. This case of disseminated tuberculosis infection maybe related to nutritional or social factors or may represent an example of reduced in ate resistance against tuberculosis infection.