The major factors underlying the seeding of tumor cells during laparoscopy are mechanical, with CO2 playing only a secondary role. The peritoneal wound is of great importance, especially in advanced tumor stages, when cells are present within the abdominal cavity. Most reported port-site metastases were found within the extraction port when no protective measures were taken. Gasless laparoscopy is no solution to the problem, since numerous port-site metastases have been described after thoracoscopy, during which no C02 is used. The surgeon's role in the seeding of tumor cells is based on tumor perforation, excessive manipulation, and replacement of trocars. This presumably explains the large differences (0% and 21 %) in the reported incidence of port-site metastases. Prospective studies now show that it is possible to keep the incidence of abdominal wall metastases to about 1%-which is comparable to that seen in open surgery-by the use of a meticulous operating technique and preventive measures.