Wilms tumor (WT) occurs infrequently in adults. Even rarer is adult WT with extension by direct intravascular spread into the right side of the heart. The present report describes a WT with intracaval and intracardiac extension in a 38-year-young man. In addition, thrombus extension above the infrahepatic IVC represents a major technical topic for surgeons because of the possible occurrence of uncontrollable hemorrhages and tumor fragmentation. We report the results of a surgical approach to caval thrombosis including the isolation of the IVC from the liver as routinely performed during liver harvesting. The morphologic and immune-histochemical findings confirmed the diagnosis.