Abstract: Objective To investigate the correlation between the insertion/deletion (I/D) polymorphism of angiotensin Ⅰ-converting enzyme gene (ACE) and cancer of colon. Methods Polymerase chain reaction (PCR) was served to detect insertion/deletion genotypes and I/D alleles of ACE gene in peripheral blood of 30 colon cancer patients, 30 normal persons as control. Results In colon cancer patients, the frequencies of genotypes of DD, ID and Ⅱ of ACE gene were 6.67%，36.67% and 56.66%, and I/D alleles were 93.33% and 6.67%, respectively. In contrast, the frequencies of genotypes of DD, ID and Ⅱ of ACE gene were 16.67%，53.33% and 30.00% and I/D alleles were 83.33% and 16.67% respectively in normal control. The distribution of DD, ID and Ⅱgenotypes of ACE gene between two groups was significant (P<0.05). On the contrary, I/D alleles between two groups was not significant (P>0.05). Conclusions There was an I/D polymorphism of ACE gene in colon cancer patients, and the distribution of II genotype were markedly higher than that in the control, which might be correlated to the prevalence of colon cancer.