OBJECTIVE: Estramustine is an stable estradiol and nitrogenated mustard conjugatewith antymicotic properties. Currently, with the appearance of chemotherapy and new molecules, estramustin acetate is not a drug of choice for castration resistant prostate cancer.METHODS: We describe two patients with castration resistant prostate cancer under treatment with estramustine acetate and complete biochemical response and stable disease. We review the literature to elucidate if the drug should be stopped and changed for the new molecules that have demonstrated survival increase. RESULTS: To our knowledge, there are not data in the literature to either solve the questions posed or shed light regarding cumulative toxicity due to prolongued use of estramustine acetate. CONCLUSIONS: We recognize that these clinical cases do not translate that estramustine acetate is a first line treatment for patients with CRPC. Nevertheless, they translate the heterogeneity of CRPC. It would be interesting to investigate the combination of new agents with estramustine acetate as well as the search of biomarkers that enable selection of candidates who could respond to estramustine acetate.