Purpose: The generalization of routine fetal US controls has led to an increase in the detection of congenital fetal anomalies, including congenital tumors. Fetal tumors are a unique group of neoplasms with an unique biologic behaviour. The extension of the mass as well as the determination of the organ of origin of the tumor are crucial factors to evaluate the prognosis and viability of the fetus. The purpose of this communicatio is to review the diagnostic accuracy of fetal MRI in the characterization of prenatal tumors detected in US. Methods and materials: We retrospectively reviewed all fetal MRI performed at our institution with suspicion of fetal tumors at the prenatal US. MRI reports were compared with US reports and with the final diagnosis, obtained by clinical reports, post-natal imaging methods and autopsy reports. Results: Between 01.01.00 and 15.12.2008, 170 fetal MRI were practiced at our institution. In 9 cases, indication for MRI was the suspition of fetal tumors at prenatal US, including 3 tumors of head, 3 thoracocervical and 3 abdominal. MRI revealed the anatomic extension and the organ of origin of the tumor in all cases. MRI characterized the lesions correctly in 6 cases and provided additional information to US in the other 3 cases. Conclusion: The excellent anatomic detail provided by fetal MRI help to characterize the congenital tumors, to recognize the origin and the extension of the tumor and to limit the possible final diagnosis. This information may be useful to decide the therapeutic approach of the patient.