Background: Quality of life has become a part of the evaluation criteria for cancer therapy. The aim of this study was to evaluate the quality of life in breast cancer patients under chemotherapy regimens that contained doxorubicin and cyclophosphamide (AC) compared to paclitaxel and gemcitabine (PG).Methods: This cohort study evaluated 100 women with breast cancer treated by doxorubicin and cyclophosphamide or gemcitabine and paclitaxel regimens. We used the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire- Core 30 to assess health related quality of life at the beginning and end of chemotherapy. Data were analyzed by the independent t-test at a significance level of 0.05.Results: Most of the 100 patients were married (68%), aged 41-50 years (36%), non-college educated (76%), and had insurance (97%). The mean quality of life scores at the first session of chemotherapy and prior to the onset of treatment-related adverse events were 71.33 for the doxorubicin and cyclophosphamide groups and 71.15 for the gemcitabine and paclitaxel groups. Analysis of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 at the last chemotherapy session showed that the quality of life in both groups deteriorated as a result of side effects. The mean of quality of life scores at the first session of chemotherapy were 66.49 for the doxorubicin and cyclophosphamide group and 59.99 for the gemcitabine and paclitaxel group.Conclusion: Strategies to improve the emotional and role functions of the patients who undergo treatment should be given priority. Financial difficulties faced by breast cancer patients should be addressed from a policy making level at the initiating health financing system.