The ovarian hyperstimulation syndrome (OHSS) is an iatrogeniccomplication of ovarian stimulation occurring during the luteal phase orduring early pregnancy.It was appeared to be a possible complication of the induction ofovulation by almost every agent used for this purpose.The most common form occurs a few days after follicular rupture orpuncture, when follicular growth has been medically induced by using eitherclomiphene citrate or gonadotrophins.Ovarian hyperstimulation syndrome is thought to result from increase incapillary permeability of the mesothelial surface, which leads to a depletionof intravascular volume and its secondary hemodynamic consequences.To minimize risk of OHSS, endogenous pregnancy- derived hCG maybe eluded by judicious cryopreservation of all embryos.Treatment of acute phase relies only on an empirical and symptomaticapproach. The general approach will be adapted to the level of severity.Specific approach such as paracentesis, pleural puncture and surgicaltreatment are included in line of treatment.