Abstract: ObjectiveTo study the relationship of DAL-1 downregulation and carcinogenesis of colorectal adenocarcinoma. Methods RT-PCR was used to detect DAL-1 mRNA expression in colorectal cancer cell lines and colorectal adenocarcinoma tissues.BSP and MSP were performed to examine the DAL-1 promoter methylation status in colorectal cancer cell lines and colorectal adenocarcinoma tissues.5-aza-dC treatment was performed to verify the promoter methylation status of DAL-1 in colorectal cancer cell lines. Results Expression of DAL-1 was found in colorectal cancer cell lines; there was no significant difference between DAL-1 expressions among the cell lines.DAL-1 was significantly reduced in a portion of colorectal adenocarcinoma tissues.Frequency of DAL-1 downregulation was significantly higher in patients with lymph node metastasis or in Dukes C and Dukes D (P＜0.05).DAL-1 promoter methylation was rare phenomenon. Conclusion Downregulation of DAL-1 plays an important role in carcinogenesis of colorectal adenocarcinoma, especially in advanced colorectal adenocarcinoma.However, the gene promoter methylation doses not regulate the expression of DAL-1.