Even though it is accepted that women with breast cancer should not receive estrogen therapy, doubts have been expressed as to the validity of this policy. In recent years opposition to this practice has been voiced more adamantly. The results of the Women's Health Initiative (WHI) study, published in July 2002, question the safety margin of estrogen therapy (ET) or hormone therapy (HT) in menopause. Whether this concern is applicable to breast cancer survivors is unclear as these women were not addressed by the study. In light of the uncertainties raised by the study and particularly the ongoing controversy about breast cancer patients, a review of the literature published prior to March 2003 was undertaken. The information gathered on the topic comes from 10 uncontrolled studies and 11 case-controlled studies, 8 retrospective and 3 prospective, carried out over the past decade. The experience encompasses 1,558 breast cancer survivors treated with ET or HT. Overall, the recurrence rate accrued from the uncontrolled studies is 7.3% (53 of 728). The average rate culminating from 11 case-controlled studies is 10.7% (99 of 830) (2.6-15.4%) in treated patients vs. 20.3% (739 of 3,640) (2.3-29.5%) in their untreated counterparts. This review revealed no increase in recurrent disease among treated patients but is not conclusive as some studies that have been flawed by biases and confounders. The fact that only 2 studies were case controlled and prospective as well as randomized, and considering concerns raised by the WHI study, it seems that many more such trials will be necessary before this controversial issue will be settled.