The Mediterranean diet (MD) is a known protective factor for head and neck cancer (HNC); however, there is still a lack of studies investigating this association by HNC subsite. The aim of the present study was therefore to evaluate the association between adherence to MD and HNC overall and by cancer subsite, as well as the effect of the individual food components on HNC risk. A case–control study was carried out at the Gemelli Hospital of Rome (Italy). A total of 500 HNC cases and 433 controls were interviewed. Dietary intake was assessed through a validated food frequency questionnaire that collected information on over 25 food items. Odds ratios (ORs) and 95% confidence intervals (CI) of HNC were calculated using a multiple logistic regression model. We found a reduced risk of both oral cavity and pharynx cancer (OR=0.61; CI: 0.54–0.70) and larynx cancer (OR=0.64; CI: 0.56–0.73) with increasing adherence to MD. We also found a high consumption of fruit, vegetables, and legumes to be significantly associated with a lower risk of larynx as well as oral cavity and pharynx cancers. Our study showed that adherence to MD acts protectively against HNC overall and by cancer subsite.