Before planning an assisted conception treatment cycle, a thorough assessment of the woman's hormone profile and ovarian reserve is essential to aid the decision on the appropriate protocol for controlled ovarian hyperstimulation (COH). There is insufficient evidence to recommend the use of one type of gonadotrophins over another. There is no benefit of luteinising hormone (LH) supplementation in cycles stimulated with follicle stimulating hormone alone in an unselected population. There is some evidence to suggest a potential benefit of LH supplementation in patients with a history of poor ovarian response to stimulation and in those older than 35 years. The long gonadotrophin releasing hormone (GnRH) agonist protocol is the most widely used and is the preferred protocol in the unselected population of women undergoing COH for in vitro fertilisation or intra-cytoplasmic sperm injection. The GnRH antagonist protocol is best used for known or suspected high responders, including women with PCOS, as it reduces the risk of OHSS. There is a lack of robust evidence to suggest that the GnRH agonist protocol is better than the GnRH antagonist protocol in poor responders. The prolonged GnRH agonist protocol is advantageous in women who are undergoing COH due to pelvic endometriosis. Oral contraceptive pill pre-treatment adversely affects the IVF outcome in GnRH antagonist cycles, but not in GnRH agonist cycles.