Over the last decade, sentinel node surgery and lymphatic mapping techniques have made a great contribution to management of malignant melanoma and breast cancer. It is now clear that the sentinel node concept, as originally described in patients with melanoma, is applicable to any type of malignant tumor that has the potential to spread via lymphatics to lymph nodes. Thus sentinel node technology has now entered a new phase of discovery and treatment. This technique has great potential for individualized management of solid tumors and will be one of the most important issues for surgical oncology in the 21st century. It is also apparent that successful application of sentinel node technology requires close cooperation between surgeons, pathologists and nuclear medicine physicians.