Objective To evaluate whether letrozole enhanced follicular recruitment, embryo numbers, and pregnancy rates in poor responders undergoing IVF. Methods We reviewed all IVF cycles between January 2002 and September 2003 using letrozole at Stanford University Medical Center. The entry criteria were the requirement of at least 450 IU/d of injectable gonadotropins in a prior failed cycle, which was used as a control. Results A total of 27 charts were reviewed revealing information on 54 cycles. The number of oocytes retrieved, fertilization, embryo quality and embryos transferred yielded no statistical significance, although there appeared to be a trend toward higher numbers of each in the letrozole group. The clinical pregnancy rate was 9/27 (33.3%, P<0.001) with a viable pregnancy rate of 7/27 (25.9%, P=0.002) in the letrozole cycle. Conclusion Our study is one of the first to evaluate letrozole with in vitro fertilization. Although this study showed no difference in number of oocytes or embryos, 25.9% of these “poor responding” patients achieved a pregnancy after a failed cycle at our center. Objective To evaluate whether letrozole enhanced follicular recruitment, embryo numbers, and pregnancy rates in poor responders undergoing IVF. Methods We reviewed all IVF cycles between January 2002 and September 2003 using letrozole at Stanford University Medical Center. The entry criteria were the requirement of at least 450 IU / d of injectable gonadotropins in a prior failed cycle, which was used as a control. Results A total of 27 charts were reviewed revealing information on 54 cycles. The number of oocytes retrieved, fertilization, embryo quality and embryos transferred yielded no statistical significance, although there to have a tendency toward higher numbers of each in the letrozole group. The clinical pregnancy rate was 9/27 (33.3%, P <0.001) with a viable pregnancy rate of 7/27 (25.9%, P = 0.002) in the letrozole cycle. Conclusion Our study is one of the first to evaluate letrozole with in vitro fertilization. Although this study showed no difference in number of oocytes or embryos, 25.9% of these “poor responding” patients achieved a pregnancy after a failed cycle at our center.