In 114 patients with at least 20 oocytes retrieved, mean ovarian volumes were (hCG 176 ml, GnRHa 90.7 ml, kisspeptin 60 ml), rates of mild to severe OHSS (hCG 90.5%, GnRHa 32%, kisspeptin 10%) and rates of moderate to severe OHSS were (hCG 28.6%, GnRHa 2.7%, kisspeptin 0%). Here, KISS1 is linked to ovarian hyperstimulation syndrome.