Abstract: Objective:To study the expression of filamin-a (FLNa) in human colorectal adenocarcinoma, and determine the role of FLNa in the pathogenesis of colorectal adenocarcinoma. Methods:The samples of colorectal adenocarcinoma and normal colorectal tissues were collected from 60patients who underwent colorectal resection. Colorectal adenocarcino -ma tissues were obtained from the central part of the tumor, while normal colorectal tissues were collected from the site which was at least10cm away from the edge of the lesion. Reverse transcription polymerase chain reaction (RT-PCR) and Western blot method were used to detect the expressions of FLNa mRNA and protein in the60specimens with colorectal adenocarcinoma and normal colorectal tissues. At the same time, immunohistochemistry was conducted to detect the distri-bution of FLNa protein in colorectal adenocarcinoma and normal colorectal tissues, and to analyze the differences between two groups. All cases were confirmed by pathological diagnosis, and primary tumors were not found at other sites. No medi -cal records of preoperative radiotherapy, chemotherapy and immunotherapy were found in the groups. Results: The expres-sion of FLNa mRNA was lower in colorectal adenocarcinoma than in normal colorectal tissues (P=0.018 , <0.05). Western blot analysis revealed that the expression of FLNa protein was also lower in colorecta adenocarcinoma than in the normal colorectal tissues ( P=0.028 <0.05). Pearson correlation analysis showed that the mRNA level was in positive correlation with the protein level ( r=0.645 , P<0.05). The positively stained particles were distributed in the cytoplasm. Of the 60colorec-tal adenocarcinoma samples, 30(50%) cases were positive for FLNa expression. And of the 60normal colorectal samples, 55(91.67%) cases were positive for FLNa expression. The positive rate of FLNa expression was lower in colorectal adeno-carcinoma samples than in the normal colorectal samples (x2=50.037 , P=0.000 <0.05). Immunohistochemical analysis showed the same results as RT-PCR and Western blot. Conclusion:The specific low expression of the FLNa protein is in a high correlation with the pathogenesis of colorectal adenocarcinoma. FLNa is expected to be a new tumor marker and the new target for clinical therapy.