Patients with polycystic ovary syndrome (PCOS), hyperandrogenemia and hypothalamic ovarian dysfunction have a predisposition for developing ovarian hyperstimulation syndrome (OHSS). Choosing treatment protocols carefully, cautious stimulation, minimizing hCG dosages for ovulation induction, and refraining from embryo transfer in case of doubt, can markedly reduce the risk. In the treatment of moderate and severe hyperstimulation syndrome, adequate hydration with fluid balance, prophylaxis against thrombosis, ascites drainage when appropriate, and close monitoring and intensive-care monitoring if necessary, must be ensured. The aim of procedures in reproductive-medicine should be to achieve pregnancy rates that are as high as possible with as few side effects of the treatment as possible.