A prospective cohort study was carried out in patients assisted in the F. J. Muñiz Infectious Disease Hospital, with the aim of determining the effectiveness of highly active antiretroviral therapy (HAART) implemented as soon as the sputum smear microscopy became negative (1 to 3 months) in the survival improvement of HIV/AIDS related multidrug-resistant tuberculosis patients. The cohort was recruited from June 1997 to February 1999 and compared with a pre-HAART control group that consisted of 43 patients. The follow-up of the patients was terminated June 2000. A total of 48 patients who received HAART precociously were included. The mortality rate in this group was 31.2% and the survival time of deceased patients 15.8 +/- 8.5 months. The T lymphocytes CD4+ count was initially 40.1 +/- 30.2/microL, while at the end of the observation period it was 140.4 +/- 73.04/microL and 79.1% of these patients presented undetectable viral load. In the control group the overall mortality was 90.7% and the survival time of deceased patients 8.95 +/- 3.72 months. We conclude that the early anti-retroviral therapy, together with the treatment of the multidrug-resistant tuberculosis and of other AIDS associated diseases represent a useful approach to achieve a longer and better survival in these severely immunodepressed patients.