This chapter reviews the regimens used in controlled ovarian hyperstimulation for in vitro fertilization (IVF) in the following categories: normal, poor, and high responders. Luteal suppression with gonadotropin releasing hormone (GnRH) agonists is usually associated with higher cancellation rates, increased dosages of gonadotropins, and prolonged days of stimulation in low responders. Several studies have compared the use of GnRH antagonist with the long GnRH agonist protocols in low responders. There are two different methods of ovulatory triggers for oocyte maturation: exogenous human chorionic gonadotrpin (hCG) and GnRH agonist in antagonist cycles. Minimal stimulation protocols are being used more commonly in IVF. The use of such stimulation protocols can be applied in cases of both poor and high responders. When in vitro maturation (IVM) is performed, fertilization is usually performed with intracytoplasmic sperm injection (ICSI), and endometrial preparation with estrogen and progesterone is necessary.