Background and Objective: It is well known that menstrual period and ovarian function are affected by chemotherapy. Although breast cancer is the most common cause of chemotherapy in women and ovarian hormones have very important direct and indirect effects on overall survival, disease-free survival, and life quality of patients, but few studies have addressed the frequency and related factors of ovarian failure in breast cancer patients after receiving conventional regimens of chemotherapy. Therefore, the risk of ovarian failure after conventional chemotherapy regimens for breast cancer (with and without taxans) and the factors that influence ovarian function due to chemotherapy including patient’s age and type and dosage of drugs were investigated in this study. Materials and Methods: The cross sectional protocol of this study was conducted on 81 premenopausal breast cancer patients with regular menstruation that were candidates for chemotherapy and had not any history of prior hormonal therapy or chemotherapy. Alteration of menstrual cycles and ovarian function were evaluated by measuring blood levels of FSH and LH. Then, the role of patient’s age, type and dosage of drugs were analyzed on ovarian function. Results: Out of a total of 81 patients evaluated, 44 (54.3%) were found to suffer from ovarian failure after chemotherapy. There was also no significant difference for the risk of ovarian failure between two major groups of chemotherapy regimens. In addition, the probability of ovarian failure increased after increasing the dosage of the drug. Meanwhile, patients over 40 years were more sensitive to chemotherapy than younger ones. Conclusion: It is concluded that patient’s age is the most important factor determining the risk of chemical castration. In this respect, addition of taxans to conventional chemotherapy does not increase the risk of chemical castration.