Abstract: Objective To evaluate the expressions of PTEN，nm23-H1 and Syk in colorectal cancer and their relationships with the carcinogenesis，development，invasion and metastasis of colorectal cancer. Methods The expression of PTEN，nm23-H1 and Syk proteins in 60 cancer tissues and 30 normal colorectal mucous tissues were determined by the immunohistochemical SP method. Their correlations with clinicopathologic features were analyzed. Results The positive rates of PTEN，nm23H1 and Syk expression was 90.0％（27／30），93.3％（28／30）and 96.7％（29／30） in normal tissues，higher than 36.7％（22／60），41.7％（25／60）and 31.7％（19／60）in colorectal cancer tissues，respectively（P＜0.01）. The expression of the three proteins in colorectal cancer tissues were not associated with age，gender，tumor size or tumor location（P＞0.05）. The expressions of PTEN and Syk were significantly related with differentiation，depth of invasion，lymph node metastasis and Duke's staging. And the expression of nm23-H1 was associated with depth of invasion，lymph node metastasis and Duke's staging. The expression of the three proteins in colorectal cancer tissues were possitively related. Conclusion The expressions of PTEN，nm23-H1 and Syk in colorectal cancer are related to carcinogenesis，development，invasion and metastasis. The joint detection of these three makers can be used to determine the biological behavior and prognosis of colorectal cancer.