OBJECTIVE: Tuberculosis is one the greatest causes of mortality worldwide, but its economic effects are not well known. This study had the objective of estimating the costs to the public and private healthcare systems and to families of tuberculosis treatment and prevention. METHODS: This study was made in the municipality of Salvador, State of Bahia, Brazil, in 1999. Data for estimating the costs to the healthcare system were collected from the Department of Health, healthcare facilities and a philanthropic institution. The public and private costs were analyzed using cost accounting methodology. Cost data relating to families were collected by means of questionnaires, and included data on transportation, food and other expenses, and also income losses associated with this disease. RESULTS: The average cost of treating one new case of tuberculosis was approximately US$103. The cost of treating one multiresistant patient was 27 higher than this. The cost to the public services consisted of 65% on hospitalization, 32% on treatment, and only 3% on prevention. The families committed around 33% of their income on expenses related to tuberculosis. CONCLUSIONS: Despite the fact that the families did not have to pay for medications and treatment, given that this service is offered by the State, the costs to families related to loss of income due to the disease were very high. The proportion of public service funds utilized for prevention is small. Greater investment in prevention campaigns not only might diminish the numbers of cases but also might lead to earlier diagnosis, thus reducing the costs associated with hospitalization. The lack of an integrated cost accounting system makes it impossible to visualize costs across the various sectors.