Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic complication that is associated with modern techniques for in vitro fertilization. Extensive efforts have been made to understand the pathophysiology and to improve the management of this entity. The severe and life-threatening forms of the ovarian hyperstimulation syndrome are still challenging for critical care physicians. This article reviews the pathogenesis, epidemiology, classification, clinical manifestations, and complications of these forms of OHSS. The different therapeutic options currently available are reviewed, and a stepwise approach for the management of these patients is provided.