Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic, potentially life-threatening condition associated with ovulation induction. With increasing numbers of women receiving various ovarian stimulation protocols as part of different infertility treatments, the number of cases is likely to increase. The syndrome has a wide spectrum of clinical and laboratory findings, and is classified into mild, moderate and severe OHSS. The pathophysiology of this syndrome is unclear, and medical management has traditionally been conservative and supportive consisting of bedrest, volume expanders and replacement of fluid. When ascites is present, paracentesis under ultrasound guidance has been found to improve the condition of the patient by reducing the hydrostatic pressure. Prevention is very important, but at present it is doubtful if OHSS can be completely avoided due to the existence of a relatively small margin of safety between successful induction of ovulation and the development of OHSS.