Aim: The aim is to describe ultrasound features of duplicated inferior vena cava in fetus in order to make a challenging detection of fetal venous anomalies more feasible. Background: Duplication of inferior vena cava (IVC) is well-known and thoroughly described by adult anatomists entity. Meanwhile, there are few publications available concerning prenatally detected inferior vena cava anomalies though they are of great importance for surgeons and radiologists. Case description: We presented two cases of double IVC diagnosed in fetuses during routine ultrasound examination. Typical sonographic visualization of two venous vessels on both sides of the aorta in the transverse view of the fetal abdomen during assessment of kidneys with the same blood flow direction makes feasible the diagnosis of dual IVC. Conclusion: Visualization of two venous vessels on both sides of the aorta in the transverse view of the fetal abdomen is typical for dual IVC. Color Doppler, demonstrating the same blood flow direction in these vessels, may prove the diagnosis. Thus, though venous assessment is not currently included in standard screening protocol, it is possible to detect this venous anomaly during mandatory ultrasound assessment of fetal kidneys. Clinical significance: The inferior vena cava anomalies may be asymptomatic, but influence the adult life being of great importance during surgery, so antenatal diagnosis is crucial. During ultrasound assessment of kidneys in the transverse view of the fetal abdomen, which is done routinely, visualization of two venous vessels on both sides of the aorta should raise the suspicion of dual IVC. The duplication of IVC can be confirmed by color Doppler demonstrating the same blood flow direction in these infrarenal segments of IVC, opposite to that of the aorta. Though venous assessment is not currently included in standard prenatal screening protocol, it is possible to detect this venous anomaly during mandatory ultrasound assessment of fetal kidneys.