Background: The association of colorectal cancer with human cytomegalovirus (HCMV) is a controversial issue in cancer research. This study aimed to identify the HCMV virus in colorectal cancer tissues and to investigate the association of HCMV with colorectal cancer. In this study, 50 cancer tissue samples and 50 samples without colon cancer were studied in order to identify the HCMV virus through nested-polymerase chain reaction. The virus was identified in 15 cases of colorectal cancer tissues (15/50) and in 5 cases of normal tissues (5/50). Eight cases of adenocarcinoma tissues were in a moderately differentiated stage, and 7 cases had well-differentiated stage tissues that were positive for viral DNA. The findings were statistically evaluated at a significance level of p<0.05. The HCMV virus could playa role in creating malignancy and the progress of cancer through the process of oncomodulation.