Objective: To investigate the effect of human cytomegalovirus(HCMV) infection on the development of colorectal adenocarcinoma and its possible mechanisms.Methods: RT-PCR was used to detect the expression of immediate-early gene 2(IE2) mRNA to reflect HCMV infection while the expression of C-Jun in 84 colorectal adenocarcinoma tissues and adjacent tissues was evaluated with immunohistochemical straining.Results: The positive rate of HCMV IE2 in colorectal adenocarcinoma tissues was higher than that in the adjacent tissues(P0.01);The positive rate of C-Jun in colorectal adenocarcinoma tissues was also higher than that in the adjacent tissues(P0.01);The expression of C-Jun gene in colorectal adenocarcinoma tissues corelated with HCMV infection(P0.05).Conclusion: HCMV infection may play an important role in the development and progression of colorectal adenocarcinoma,and its mechanisms may be related with the expression of C-Jun.