In the present work, the micronuclei (MN) test was performed in buccal mucosal samples from patients with cancer, with (pre- and post-treatment) and without genotoxic chemotherapy (GC), identified micronucleated cells (MNC) and nuclear abnormalities (binucleated cells (BN), pycnosis (PN), "broken-egg" (BE), condensed chromatin (CC), karyorrhexis (KR), and karyolysis (KL). The objective was to evaluate the genotoxicity of cisplatin + 5-Fluorouracil (5-FU), carboplatin (CBP) + 5-Fluorouracil, and ifosfamide (IFO) + epirubicine (EPI) regimens. The ifosfamide + epirubicine regimen described here produced a micronucleogenic effect, whereas the regimens using platinum compounds were cytotoxic for buccal mucosal cells, which probably explain the absence of increase of micronucleated cells in these samples compared with basal levels. In patients with cancer (with and without genotoxic chemotherapy), the numbers of MNC, PN, KR, total nuclear abnormalities and KL increased, together with a decrease in BN cells and CC. On the other hand, as consequence of the cytotoxicity of the drugs, the number of binucleated cells decreased and the number of karyolytic cells increased. These results could be used as a cytotoxicity marker in the future studies for different drugs.