Burgis et al. reported the incidence of oblique vaginal septum syndrome (OVSS ) is 0.1 %～3.8 %. There are 3 types，and different types of OVSS have different clinical presentations.Induced abortion is hard for patients of OVSS with pregnancy，because of their complex reproductive tract anomalies. This article reported 3 types OVSS with unwanted pregnancy，1 case of each type. Through these cases，we can draw a conclusion that the diagnois and treatment of these patients are difficult，it tends to be ignored and easily misdiagnosed. So clinicians and sonographers should raise awareness of this kind of Müllerian duct anomalies；it is important to diagnose exactly and cure correctly.