Antipsychotics may prolong or retain telomere length, affect mitochondrial function, and then affect the metabolism of nerve cells. To validate the hypothesis that antipsychotics can prolong telomere length after oxidative stress injury, leukocytes from healthy volunteers were extracted using Ficoll-Histopaque density gradient. The mononuclear cells layer was resuspended in cell culture medium. Oxidative stress was induced with hydrogen peroxide in cultured leukocytes. Four days later, leukocytes were treated with aripiprazole, haloperidol or clozapine for 7 days. Real-time PCR revealed that treatments with aripiprazole and haloperidol increased the telomere length by 23％ and 20％ in peripheral blood mononuclear cells after acute oxidative stress injury. These results suggest that haloperidol and aripiprazole can reduce the damage to telomeres induced by oxidative stress. The experiment procedure was approved by the Ethics Committee of Faculty of Medicine of the University of S?o Paulo (FMUSP/CAAE approval No. 52622616.8.0000.0065).