SummaryTo assess the impact of raised intra-abdominal pressure associated with laparoscopy on venous return, we have used an animal model (pig) to study the effect of progressive increases in insufflation pressure on femoral venous blood outflow. As a second variable, the effect on flow of the reverse Trendelenburg position was also assessed. Evidence of any adaptation in venous blood flow to the increased intra-abdominal pressure was assessed during a prolonged surgical procedure. These studies have shown that femoral venous blood outflow in the pig is markedly depressed at insufflation pressures of 10 to 20 mm Hg. The reverse Trendelenburg position accentuates this reduction in flow, and there was no sign of adaptation to this depressed flow during a laparoscopic Nissen fundoplication. These findings have clear implications for the potential of deep venous thrombosis/pulmonary embolism (DVT/PE) following prolonged therapeutic laparoscopy.