PURPOSE: Monoclonal antibody Ki-67 has been employed to evaluate the growth fraction of various tumors. The purpose of this study is to determin the prognostic value of the Ki-67 index for colorectal cancer. METHODS: The Ki-67 index was investigated by counting the immunohistochemically stained cells. We described this as the permillage. We reviewed the test results of 36 colorectal cancer patients and we compared the Ki-67 index with other clinical factors. RESULTS: There was no correlation between the Ki-67 index and the other established risk factors, and only the number of invaded lymph nodes and their degree of differentiation were related with the Ki-67 index. CONCLUSION: The Ki-67 index is an important marker of the growth fraction of tumor. The pattern of tumor growth is determined not only by the growth fraction, so the discovery of other parameters that can reflect tumor growth and the Ki-67 index can help the patients with respect to their prognosis & treatment.