The study aimed at evaluating the influence of MTHFR 677C>T and NQO1 609C>T polymorphisms in toxicity and response to chemotherapy in breast cancer patients. These two genes are involved in the folate homeostasis and bioactivation of chemotherapeutic drugs, respectively. In this study, 243 patients treated with FEC/FAC/methotrexate chemotherapy regimen were recruited and followed up for toxicity (NCI-CTCAE ver. 3). While out of 243 patients, 115 patients who received neo-adjuvant chemotherapy (NACT) were followed for treatment response. Genetic analysis of MTHFR 677C>T and NQO1 609C>T was done by PCR-restriction fragment length polymorphism. We found significant association of variant genotype (TT) of NQO1 609C>T with grade 2-4 toxicity [OR 0.33 (0.13-0.88), P = 0.027] and with grade 2-4 anemia [OR 0.34 (0.12-0.95), P = 0.041]. However, no association of MTHFR 677C>T was seen with either response to NACT or drug-induced toxicity. The study provides useful information for prediction of clinical outcomes in breast cancer patients in terms of NQO1 609C>T by evaluating its association with chemotherapy-induced toxicity.