To measure alterations of hemodynamics in the portal vein during increasing intraabdominal pressure due to carbon dioxide insufflation an established animal model of laparoscopic surgery in the rat was extended by implantation of a perivascular flow probe. Using this technique an adequate flowmetry of the portal vein was achievable in all animals. The installation of a CO2 pneumoperitoneum with elevating intraabdominal pressure led to a linear decrease of portal venous flow. This might compromise liver function and cell-conveyed immunoresponse in the liver during laparoscopic surgery.