Controlled ovarian hyperstimulation (COS) proved to increase the success rate of in vitro fertilization (IVF), and the results achieved by most treatment centers exceed spontaneous conception rates in healthy, fertile couples. The in vitro maturation (IVM) technique aims to make use of the multiple immature oocytes that already exist in the ovaries of a reproductive-aged woman. A short course of gonadotropin administration has been suggested to improve the clinical outcome of IVM cycles through increasing developmental competence of immature oocytes and/or the number of in vivo-matured oocytes collected in an IVM cycle. Pregnancy rates seem to be significantly higher when an in vivo-matured oocyte has been collected. Young women with high antral-follicle counts seem to have the highest pregnancy rates with IVM. Once a successful IVM program has been implemented, all assisted reproduction treatment (ART) laboratory procedures can be performed with in vitro-matured oocytes if the need arises.