Objective： To evaluate the relation between DNA contents, 2c deviation indexes(2cDI) of colorectal cancer cells,changes of some gastrointestinal hormones levels,and the cancer clinical pathologic features. Methods: In 40 patients with colorectal cancer, DNA contents, 2cDI of the tumor cells (determined by automatical imaging cytometry), serum gastrin, plasma somatostatin(SS),tumor SS, cancer-adjacent mucosa SS and cancer-distant mucosa SS levels (assayed by RIA), and the cancer clinical pathologic features were analyzed by multiple variable stepwise regression with a computer. Results: The increases of tumor SS closely accompanied by the decrease of the cancer cell DNA contents or 2cDI (P<0.01). Cancer-adjacent mucosa SS had a significant positive correlation to the cancer cell DNA contents or 2cDIs (P<0.05 and P<0.01, respectively). The cancer cell DNA contents and 2cDIs increased significantly in patients with rectal cancer (P<0.01). Conclusion: The endogenous SS may play an important role in the regulation of DNA synthesis in cancer cell, elevating the tumor SS level and keeping the cancer-adjacent mucosa SS at high level, thus inhibiting the DNA sythesis in colorectal cancer cell.