Corifollitropin alfa has been shown to result in significantly more oocytes compared to daily recombinant follicle stimulating hormone (recFSH) (Devroey et al., 2009), probably due to the higher circulating FSH activity during the first days of stimulation. For this reason, the use of corifollitropin alfa might be beneficial in poor responders in whom the number of oocytes retrieved is crucial for success. The purpose of this study is to evaluate the effectiveness of corifollitropin alfa treatment compared to daily recFSH in terms of the number of oocytes retrieved in a defined population of poor responder patients undergoing intracytoplasmic sperm injection (ICSI) using gonadotrophin releasing hormone (GnRH) antagonists.