Ovarian hyperstimulation syndrome (OHSS) is one of the most serious iatrogenic complications in women undergoing controlled ovarian stimulation (COS) during in vitro fertilization (IVF). There is no single established protocol for its prevention. The prevention strategies can be broadly divided into two categories. Primary prevention aims to identify women at risk of OHSS well before the start of COS. It classifies women into three groups: low risk, normal risk, and high risk of OHSS, thus helping in the planning of individualized treatment regimens. Secondary prevention, on the other hand, comprises methods that can be used to prevent progression to OHSS in patients who are already showing an excessive response during ovarian stimulation. Thus, tweaking the ongoing stimulation may be attempted in order to curb this excessive response. Strategies that have been implemented to this effect include reducing the dose or duration of gonadotropin stimulation, addition of recombinant LH in the late follicular phase, and coasting. The utilization of these strategies may not completely eliminate the risk of OHSS in every patient, but it can certainly help in reducing its incidence. The advent of GnRH antagonist protocols, enabling the use of safer GnRH agonist triggers, and the excellent results with embryo vitrification, provides more successful strategies to prevent OHSS as compared to making adjustments in follicular phase stimulation alone.