The drug-drug interactions between antiretrovirals and carbamazepine or oxcarbazepine were evaluated in a clinical setting using therapeutic drug monitoring (TDM) trough concentrations collected from HIV+ patients treated concomitantly with carbamazepine or oxcarbazepine and antiretrovirals for at least 3 months. HIV-infected patients not concomitantly treated with antiepileptic drugs and who underwent TDM for antiretrovirals in the previous 2 years were considered as controls. Eleven HIV-positive patients prescribed carbamazepine (n=7) or oxcarbazepine (n=4) were identified. All the TDM evaluations for carbamazepine and oxcarbazepine were within the therapeutic ranges. Trough concentrations for atazanavir were ~65% lower when compared with HIV-infected patients not treated with antiepileptic drugs (190 ± 91 versus 546 ± 380 ng/ml, respectively). Co-administration of carbamazepine or oxcarbazepine with atazanavir should be avoided owing to the potential risk of virological failure; the adoption of TDM is strongly advisable, eventually combining with increased antiretroviral doses.