Several approaches have been proposed for the management of OHSS that reduce, but do not completely eliminate the incidence of human chorionic gonadotrophin (HCG)-induced early severe OHSS. Three women diagnosed with polycystic ovarian syndrome underwent ovarian stimulation for IVF using a gonadotrophin-releasing hormone (GnRH) antagonist protocol. Three days after oocyte retrieval, severe early OHSS was diagnosed by analysis of haematocrit (Ht), white blood cell (WBC) count, serum urea, and ultrasonographic assessment of ovarian size and ascitic fluid. On the same day, antagonist administration was re-initiated and continued daily for a week, while all embryos were cryopreserved. No progression of severe early OHSS was observed in any of the patients. A marked decrease of Ht, WBC count, ovarian volume and ascitic fluid was observed during 1 week of follow-up, and none of the patients required hospitalization. GnRH antagonist re-initiation might represent a new strategy for flexible management of patients with established severe early OHSS. Based on the flexibility of the approach, if severe OHSS does not occur, patients may proceed to embryo transfer, while if severe early OHSS ensues, antagonist administration combined with embryo cryopreservation appear to be associated with prevention of life-threatening OHSS, facilitation of regression of severe OHSS to a moderate form and avoidance of patient hospitalization.