We reported a case of 27 year old gravida 3, parity 1, abortion 1 referred to our clinic with the diagnosis of preterm labour and polihydramniosis at 34. gestational week. The ultrasonografic examination of the patient, with no antenatal follow up before, revealed a fetal biometry of 33 weeks and polyhydramniosis. A 63x66 mm solid mass with reguler border which involves the whole right kidney was determined with ultrasonografic examination of the fetus. Blood flow of the mass was also demonstrated with colour-doppler ultrasound. There was no additional pathology in the other systems and left kidney. The patient was counselled with pediatric nephrology
and pediatric surgery departments. Cesarean section was performed with the endication of preterm rupture of membranes and previous history of cesarean section. 2600 gr male baby was delivered. 70x73mm solid mass was confirmed with neonatal examination of the fetus
and nephrectomy was performed on 16th day by pediatric surgery. Pathological examination of the specimen demonstrated congenital mesoblastic nephroma.