Patients with HIV can often present a diagnostic challenge and may have atypical presentations of more common diseases. This case demonstrates а HIV (+) patient with an advanced immunosuppreession with tuberculosis complaining about 2 months before admission to the hospital of backache, anorexia and weight loss. On investigation she was found to have unilateral tuberculous psoas abscesses, diagnosed microbiologically and with a CT scan. Complex treatment (surgical, tuberculostatics, antiretroviral) was performed with a good effect. A review of the literature shows that this is a rare presentation of an already unusual problem, with subtle signs requiring a high index of clinical suspicion. However, with HIV-positive patients more likely to present with extrapulmonary tuberculosis, there is need for increased awareness of this diagnosis.