BACKGROUNDTwenty‐five percent of all women with breast carcinoma are premenopausal and are at risk for chemotherapy‐induced menopause with long‐term side effects. Although there is considerable documentation of the rates of chemotherapy‐induced amenorrhea with classic adjuvant regimens, there are inadequate data that address the impact of taxanes on menstrual function in this setting. The objective of this analysis was to determine the incidence of long‐term amenorrhea (≥ 12 mos) in women with breast carcinoma age 40 years and younger after adjuvant anthracycline and taxane‐based chemotherapy, with or without subsequent tamoxifen.METHODSThe authors identified 235 premenopausal women with breast carcinoma age 40 years or younger who were treated with adjuvant anthracycline and taxane‐based chemotherapy at Memorial Sloan‐Kettering Cancer Center from January 1997 to June 2003.RESULTSOne hundred sixty‐six patients met all eligibility criteria and had sufficient follow‐up for evaluation. The median age of patients at diagnosis was 36 years (range, 27–40 yrs). All patients had regular pretreatment menses, 25 patients (15%) developed long‐term amenorrhea, and 141 patients (85%) resumed menstruation. Eighty‐two patients (49%) also received tamoxifen: The incidence of amenorrhea among them was 17%. There was a statistically significant association between age and the development of amenorrhea, with older women at higher risk. (P < 0.01)CONCLUSIONSThe sequential addition of a taxane to standard adjuvant anthracycline‐based chemotherapy did not appear to produce a high rate of chemotherapy‐related amenorrhea compared with historic controls. To increase the information available to assist young patients who are considering adjuvant therapy, prospective studies should incorporate menstrual function ascertainment by patient‐reported history and assays of ovarian function. Cancer 2005. © 2005 American Cancer Society.