This article reviews the relationship between estrogen replacement therapy (ERT) and hormone replacement therapy (HRT) in the development of endometrial, ovarian, and breast cancers. The wisdom of HRT in survivors of ovarian and endometrial cancers is reviewed by critically analyzing recent data. Because of methodological limitations in the reported studies, there are no definite data to support the safety of ERT and HRT in survivors of ovarian or endometrial cancer.