The suppression of plasma viral loads in HIV infected patients to less than the limit of quantification of the most sensitive commercially available assays and the coincident improvement in CD4 T cell counts is associated with a decrease in the risk of new opportunistic infections in this patients. The descent at the morbibility and mortality is specialy important since the introduction in 1996 the hard activity antirretroviral therapy (HAART). However, prolonged treatment with combination regimens can be difficult to sustain because of problems with adherence and toxic effects. All antiretroviral drugs can have both short-term and long-term adverse events. The risk of specific side effects varies acording to specific drug, drug class and even, individual susceptibility. A better understanding of the adverse effects of antiretroviral agents is of interest to try to optimize therapy in HIV infected patients.