Prevention of ovarian hyperstimulation syndrome (OHSS) during ovarian stimulation is the important step in the management of this serious complication, which is associated with serious morbidity and possible mortality in a young healthy woman. In two recent meta-analyses comparing the outcome of gonadotropin-releasing hormone (GnRH) agonist versus antagonist, both showed that the incidence of OHSS was reduced in the antagonist protocol. Coasting helps to reduce the incidence of OHSS markedly, however, complete prevention with coasting was not possible. The effectiveness of human albumin administration in prevention of OHSS was published in a Cochrane review. A low dose of human chorionic gonadotropin (hCG) appears to reduce the incidence of OHSS without compromising success rates. The administration of hCG leads to vascular permeability enhancement resulting in loss of fluid and the full blown syndrome. The dopamine agonist cabergoline can reverse VEGFR-2 and the increased vascular permeability.