Mycobacterium avium complex (MAC) infections in AIDS are increasingly common and contribute to the mortality in severe immunocompromised patients. In this paper, we review the published studies on the prevention of the MAC infections. Rifabutin and the new macrolides (clarithromycin, azithromycin) are shown to be effective in the primary prevention. However, they can fail and are difficult to manage with the antiretroviral treatment, specially antiproteases and prevention of the other opportunistic infections. For the prevention of the relapse of the MAC infections, it is necessary to give a prolonged treatment with a bio-therapy associating at least a new macrolide with rifabutin or ethambutol, which is also difficult to manage with the other treatments.