INTRODUCTION: In breast cancer, the regimen used for the neoadjuvant and adjuvant nonmetastatic setting is the 4 cycles of Adriamycin and cyclophosphamide(AC) followed by Docetaxel(T), Docetaxel and Carboplatin regimens(T+Ca) and Docetaxel + Trastuzumab(T+Tr) (1,2). METHODS: A prospective open-label observational comparative study to evaluate the incidence of anemia and thrombocytopenia among the three regimens of chemotherapy regimen I AC-T, Regime II AC-T+Ca, Regimen III AC-T+Tr. All enrolled patients received pegfilgrastim/filgrastim. The total number of enrolment of patients in the study was 124 and distributed as 38,40,46 in three regimens respectively. RESULTS: The mean incidence of anemia in the regimen I , regimen II and regimen III in overall 8 cycles, it was 7.1± 1.5, 7.4+1.1, 7.1+1.5 respectively. There was no statistically significant difference in the mean incidence of anemia among the 3 study groups. A total of 109 episodes of thrombocytopenia out of 992 cycles of chemotherapy (10.9%) were observed.The mean incidence of thrombocytopenia in regimen I in the initial 4 cycles was 0.1+ 0.5; in the final 4 cycles, 0.2+ 0.6; and in the overall 8 cycles, 0.3+ 1. There was no statistically significant difference in the mean incidence of thrombocytopenia among the 3 study regimens. CONCLUSION: There was no significant difference in the incidence of anemia among the 3 regimens in the initial 4 chemotherapy cycles, final 4 chemotherapy cycles, or overall 8 cycles of chemotherapy.Among the overall 8 cycles of chemotherapy, there was no statistically significant difference in the mean incidence of thrombocytopenia among the three regimens.