Objective:To explore the expressions of inhibitors of DNA binding 1 (Id-1)and matrix metalloproteinase-9(MMP-9)in human colorectal adenocarcinoma tissues and study their correlation with the progression of colorectal adenocarcinoma. Methods:The expressions of Id-1 and MMP-9 in 50 specimens of coloreetal adenocarcinoma tissues and 50 specimens of normal eolorectal tissues were detected by immunohistochemistry,reverse transcription polymerase chain reaction (RT-PCR),and Western blotting assay. Correlations between the expressions and clinicopathological features were analyzed. Results:The positive rates of Id-1 and MMP-9 in colorectal adenoeareinoma tissues were 72.00% and 78.00%,respectively,while in normal colorectal tissues were 24.00% and 22.00%,respectively. The differences were significant (all P < 0.01). Expression of Id-1 was positively related with expression of MMP-9 in colorectal adenocarcinoma tissues (r=0.469,P=0.000). Expression levels of Id-1 and MMP-9 were correlated with the depth of tumor invasion,TNM stage,lymph node metastasis,vessel invasion,and liver metastasis (all P < 0.05),but not with age,gender,tumor size,and differentiation degrees(all P > 0.05). The results of RT-PCR and Western blotting assay were consistent with those of immunohistochemistry. Cox multi-factor analysis showed that Id-1 and MMP-9 expressions were independent prognosis factors for colorectal adenocarcinoma. Conclusion:The expression levels of Id-1 and MMP-9 have a high correlation with the invasion and metastasis of colorectal adenocarcinoma,and joint detection of the above indicators to judge the invasion,metastasis and prognosis of colorectal cancer has important guiding significance.