Introduction: Breast cancer is the commonest cancer in urban Indian females, and the second commonest in the rural Indian women. The estimated number of breast cancer cases in India during 2012 was 145,000 cases with an incidence rate of 25.8 per 100,000 women. In Kerala, Breast cancer has an annual incidence of 14.9/100,000 population. This study was carried out with an objective to identify the proportion of thrombocytopenia and the requirement of platelet transfusions in these patients. Material and methods: This was a hospital based prospective study, done in the Department of Transfusion medicine for a period of one and a half years from January 2016 to June 2017. As per the inclusion criteria 125 consecutive cases who underwent chemotherapy for Carcinoma Breast at Department of Radiotherapy, Govt. Medical College, Thiruvananthapuram were included for the study. The requirement of platelet transfusions were assessed in these patients. Data was analysed with SPSS software (version 21). Results: Among the 125 patients, thrombocytopenia was noticed in 5.4% study population in prechemotherapy phase, majority having only grade I thrombocytopenia. In Post chemo phase thrombocytopenia was observed in 11.2% of the study group, grade I thrombocytopenia in 8.8% and grade II thrombocytopenia 2.4% of patients. Platelet transfusion was required in 5.4% of the patients during chemotherapy. Conclusion: Due to the high prevalence of chemotherapyinduced hematological complications, even mild degrees of thrombocytopenia should be detected and evaluated before commencing chemotherapy. Platelet transfusion should be reserved for patients who were really required. This study gives an insight regarding the proportion of thrombocytopenia in patients with carcinoma breast undergoing chemotherapy and their platelet transfusion requirements, which will help in taking care of these patients and inventory management of the blood banks.