The 5-year survival of patients with colorectal cancer UICC stage I and II ranges from 70% to 80%. Therefore, at least 20% to 30% of these patients develop recurrent disease, caused by hematogenic or lymphogenic tumor cell dissemination. Using immunohistochemical or molecular biological methods, disseminated tumor cells can be detected in lymph nodes in a high proportion of patients in UICC stage I or II. The detection of disseminated tumor cells could help to identify a subgroup of patients at risk for disease relapse who could benefit from adjuvant therapy. Lymphogenic tumor cell dissemination seems to be a very common event in early colorectal cancer, preceding hematogenic tumor cell dissemination. Although these observations appear to confirm the therapeutic importance of meticulous lymph node dissection, their prognostic relevance has yet to be determined in prospective studies.