Various methods were used to estimate the proliferative activity of tumor cells, including the Ki-67 labeling index, proliferating cell nuclear antigen the Brdurd labeling technique, the mitotic index, and flow cytometric analysis. Several recent reports have indicated that these parameters of cellular proliferation may be of some prognostic significance. In this study, cellular proliferative activities in 105 gastric cancer patients were analyzed with various clinicopathologic factors by using the ki-67 labeling index. The monoclonal antibody to the Ki-67 antigen detects a nuclear antigen expressed in all phases of the cell cycle except G0, and has been widely used to determine the proliferative activity of neoplastic tissues. The Ki-67 labeling index (the number of Ki-67 positive tumor cells divided by the sum of Ki-67 positive and negative tumor cells) was derived by counting 1,000 cells in each case. A significant difference was noted between advanced and early gastric cancer. Advanced gastric cancer lesions showed a mean value of 32.15, about 1.7 times greater than that of the early gastric cancer lesions, 18.32 (p=0.001). The presence or absence of lymph node metastasis also showed a significant difference. The mean value of Ki-67 with lymph node metastasis was 31.78 whereas that without metastasis was 19.48 (p=0.001). There was also a significant difference in Ki-67 LI between each stage (p=0.010). However, no statistically significant differences were noted in age, sex, tumor location, histological differentiation, lauren type, and tumor size. Conclusion : High Ki-67 LI may suggest active cellular proliferation and increased risk of advanced cancer and lymph node metastasis. Ki-67 LI may be used as a possible independent parameter to predict the outcome of gastric cancer treatment.