Given roles of HPV and genetic factors in cancer risk, we evaluated associations of HPV16 seropositivity and five E2F2 promoter variants with squamous cell carcinoma of oropharynx (SCCOP) and squamous cell carcinoma of oral cavity (SCCOC) risk in a case–control study of 325 patients and 335 cancer-free matched controls. We found that HPV16 seropositivity was significantly associated with SCCOP risk (aOR, 5.4, 95%CI, 3.7–8.9) but not SCCOC (aOR, 0.8, 95%CI, 0.4–1.5), while each E2F2 polymorphism had no significant main effect on SCCOP and SCCOC risk. However, after combining HPV serological status and E2F2 promoter variants together, the modification effect of HPV serology and individual or combined risk genotypes of five polymorphisms on risk was significantly higher among SCCOP than among SCCOC. Furthermore, the stratified analysis by smoking status showed that all such modifying effects aforementioned on SCCOP were more pronounced in never smokers than in smokers. These findings are in agreement with those of previous studies, in which a majority of SCCOP were caused by HPV infection, whereas most SCCOC were found to be caused by smoking and drinking. Taken together, these findings indicate that the risk of SCCOP as opposed to SCCOC associated with HPV16 seropositivity was modified by E2F2 promoter variants either individually or jointly, especially in never smokers.