Background: Human papillomavirus (HPV) is one of the most common sexually transmitted infections worldwide and the association between HPV infection and genital cancers has been well established. This study concerned the possible role of HPV infection in colorectal carcinoma (CRC) in the Iranian population. Materials and Methods: We examined 80 tissues obtained from patients with colorectal cancer consisting of 58 colon cancer samples and 22 rectal cancer samples and 80 tissues from patients with unremarkable pathologic changes as matched controls by sex, study center and anatomical sites. HPV infection and genotypes were detected using nested PCR and sequencing methods, respectively. Results: HPV DNA was detected in 5/80 (6.25%) cases including 1 of 22 (4.54%) patients with rectum cancer and 4 of 58 (6.9%) patients with colon cancer and 1/80 (1.25%) of controls. Furthermore, HPV-18 was detected as the most frequent type and we found no significant correlation between prevalence of HPV infection and anatomical sub- sites. Conclusions: Although a causal relation between human papillomavirus and colorectal cancer was not found through this study, analysis of medical records pointed to a possible role for high- risk types of HPV in increasing the potential of aggressiveness in colorectal cancer. This study shows a particular frequency of HPV genotypes in patients with colorectal cancer in Iran. Since HPV vaccines are limited to a few types of virus, using cohort studies in different geographical zones to screen for patterns of HPV infection in different organs might increase the efficacy and optimization of the current vaccines.