, , 2, , (Received 14 January, 2009; Accepted 17 June, 2009)AbstractBackground and purpose: Although adjunct chemotherapy may increase life in non-menopausal breast cancer patients, however, it may cause short-term complications such as nausea, vomiting, alopecia, as well as long-term complications in ovarian failure and premature menopausal. The objective of this study was to investigate chemotherapy-induced secondary amenorrhea in non-menopausal women with breast cancer.Materials and methods: A descriptive design (case series) was preformed on fifty breast cancer patients, non-menopausal (normal mense) and chemotherapy in Ramsar Emam Sajad Hospital Oncology unit from 2007 to 2008. Sampling was consecutive. Data gathering method was questionnaire & blood sampling (FSH & Progesterone) for prior and 12 months after the end of chemotherapy. Data was analyzed by paired-t, independent-t and one-way ANOVA tests.Results: Results showed that 62% of patients were amenorrhea 12 months after the end of chemotherapy. Results showed that there was no meaningful relationship between age, hormone therapy, disease stage, node-positive and ER & PR status to amenorrhea; however, there was a meaningful relationship between duration of treatment, type and dose of chemotherapy to amenorrhea.Conclusion: In pre-menopausal patients with breast cancer, receiving cytotoxic chemotherapy against tumor cells, amenorrhea may occur do to ovarian failure.J Mazand Univ Med Sci 2009; 19(70): 9-17 (Persian)