Renal venous thrombosis (RVT) in neonatal period is a rare disease and usually complicated to clinical situations with reduced renal blood flow and hypercoagulability ; like acute blood loss, sepsis, shock, and birth asphyxia. RVT should be suspected in sick babies with hematuria, anemia, thrombocytopenia, enlarged kidney and acute renal failure. And the diagnosis can be confirmed by renal ultrasonography. We report two cases of neonatal renal venous thrombosis with review of literatures. One case, associated with E. coli sepsis, recovered completely, and the other, follwed respiratory distress in the neonate, revealed permanent renal functional impairment.