Objective To evaluate the relationship between leptin level in serum and clinicopathologic features of colorectal cancer. Methods ABC-ELLSA was used to detect the leptin level in 30 cases of colorectal cancer without dystrophy (cancer group) and 24 normal controls (control group). The expressions of K-ras， p53， adenomatous polyposis coli （APC） gene and delete in colorectal carcinoma gene (DCC) mRNA of the tumor were examined by RT-PCR, the levels of serum CEA and CA19-9, and other clinicopathologic features were also recorded. Results The leptin level in cancer group 〔（3.53±1.72） μg/L〕 was higher than that in control group 〔（2.27±1.01） μg/L〕, P＜0.05, and the difference was independent on gender. There were no significant differences of leptin level in different tumor stages and different tumor location （Pgt;0.05）. Leptin level of poorly differentiated tumor was obviously lower than that of well differentiated and moderately differentiated tumor （P＜0.05）. There were no associations between leptin level and the levels of CEA and CA19-9, likewise there were no associations between leptin level and the expressions of K-ras, p53, APC and DCC in tumor （Pgt;0.05）. Conclusion The leptin level of colorectal cancer patient is higher than that of normal person, which is affected by the differentiation of tumor. But there are no significant correlations between the level of leptin in serum and TNM stage, tumor location, tumor markers of serum, K-ras, p53, APC or DCC in tumor.