Objective To report a case of ovarian hemorrhage after transvaginal ultrasound-guided oocyte retrieval combined with severe ovarian hyperstimulation syndrome (OHSS). Methods A 26-year-old woman who was on therapy for infertility presented with abdominal distension and a decrease of urine after transvaginal ultrasound-guided oocyte retrieval for in vitro fertilization-embryo transfer (IVF-ET). Initial clinical presentation, ultrasound, and lab results were consistent with the diagnosis of severe OHSS. However with 4 d conservative treatments there seemed no recovery and the patient became more serious for her hemoglobin fell from 169.0 g/L to 60.2 g/L along with more abdominal fluid and a decrease of urine. Ultrasound guided paracentesis revealed an ovarian hemorrhage, and the patient underwent emergent surgery. Results The patient underwent emergent laparotomy for oophoroplasty and preservation of ovary. She got twin pregnancy in the second frozen-thawed embryo transfer (FET) cycle and delivered two female babies. Conclusion It is important to distinguish the OHSS from ovarian hemorrhage, because the ovarian hemorrhage with hemoperitoneum requires immediate operative management, whereas OHSS is nearly always managed conservatively. Clinicians must be aware that ovarian hemorrhage may be delayed in women presenting OHSS. Objective To report a case of ovarian hemorrhage after transvaginal ultrasound-guided oocyte retrieval combined with severe ovarian hyperstimulation syndrome (OHSS). Methods A 26-year-old woman who was on therapy for infertility presented with abdominal distension and a decrease of urine after transvaginal ultrasound-guided oocyte retrieval for in vitro fertilization-embryo transfer (IVF-ET). Initial clinical presentation, ultrasound, and lab results were consistent with the diagnosis of severe OHSS. However with 4 d conservative treatments there observed no recovery and the patient more serious for her hemoglobin fell from 169.0 g / L to 60.2 g / L along with more abdominal fluid and a decrease of urine. Ultrasound guided paracentesis revealed an ovarian hemorrhage, and the patient underwent emergent surgery. Results The patient underwent emergent laparotomy for oophoroplasty and preserved of ovary. She got twin pregnancy in the second frozen-thawed embryo transfer (FET) cycle and delivered Two female babies. Conclusion It is important to distinguish the OHSS from ovarian hemorrhage, because the ovarian hemorrhage with hemoperitoneum requires immediate operative management, while OHSS is nearly always managed conservatively. Clinicians must be aware that ovarian hemorrhage may be delayed in women presenting OHSS .