Abstract: OBJECTIVE: To evaluate the role of ultrasound in prenatal diagnosis of vasa praevia (VP) and to asses the risk of VP associated with different causal factors. MATERIAL AND METHODS: A retrospective study of the incidence of VP in a series of 12,063 deliveries between January 2000 and March 2005. We also studied the factors that predisposed for VP and the perinatal outcome of pregnancies. RESULTS: The prevalence of VP in our centre during this period was 0.07% (9 cases). All cases were prenatally diagnosed. The mean gestational age at diagnosis was 26 weeks. Multivariate analysis revealed the following associated factors: IVF pregnancies, bilobate or succenturiate placenta, and second-trimester placenta praevia, with an odds ratio of 7.75, 22.11 and 22.86, respectively. CONCLUSIONS: In our series, the prenatal diagnosis of all cases of VP achieved during the second-trimester scan allowed us to avoid any prenatal death related to this condition.