Duloxetine is an antidepressant which has showed valuable results, particularly in patients with major depression. This type of drugs is known to require genotoxic studies as part of their preclinical safety evaluation. In the case of duloxetine, however, there have been controversial results. Therefore, we considered it worthwhile to extend studies on the matter in an attempt to reach a conclusion. The present assay was made in mouse bone marrow to evaluate the capacity of the drug to induce sister chromatid exchanges (SCE), as well as to modify the proliferation kinetics and the mitotic index. Three doses of the antidepressant were tested (2, 20, and 200 mg/kg), besides the control mice were administered with purified water, and the positive treated animals administered with 1 mg/kg of doxorubicin. The results indicated a moderate but significant increase of SCE with the three tested doses, no effect regarding the mitotic index and a small reduction in the proliferation kinetics. Although in our assay the drug showed a lower effect, the present study agreed with a previous report that analyzed the amount of micronuclei in mouse peripheral blood, and it confirmed the relevance of evaluating the genotoxic effect of antidepressants, specifically duloxetine by applying diverse tests.