Objective: To report three cases of monozygotic twinning after IVF-ET transfer. Methods: Private practice in two different assisted reproductive technology clinics. Results: Three intrauterine monozygotic twin pregnancies occurred after IVF-ET. One of them was complicated by cord entanglement, another is progressing normal pregnancy without complication and the other was had a normal pregnancy without complication and delivered twin by cesarean section. Conclusion: The reported prevalence of multiple gestations in IVF-ET is a approximately 30%, and it is only 2.7% to be monozygotic twinning in IVF-ET. We report three cases of monozygotic twining after IVF-ET.