Vasa previa is an extremely rare condition. Consequently it is not often considered in the differential diagnosis of antepartum or intrapartum hemorrhage. Rupture of a fetal vessel may lead to sudden fetal death from exsanguination; therefore, this condition should be suspected in any antepartum or intrapartum hemorrhage. The blood that is lost should be tested for the presence of fetal hemoglobin. Other diagnostic tests to assess the degree of fetal distress are described. Four patients showing unusual presentations of vasa previa are reported. These cases demonstrate that fetal vessel rupture may occur independently of membrane rupture.