The Brazilian Unified Health System (SUS) is responsible for offering free assistance to more than 100 million Brazilians, including treatment of oral cancer lesions. Considering that the Brazilian public system aids the most vulnerable population, this study analyzed whether the origin of hospital referrals of patients with oral cancer is associated with socioeconomic factors. A cross-sectional study was carried out from cancer hospital records of the National Cancer Institute (RHC-INCA), considering the primary locations (C00 to C06) diagnosed between 2016 and 2019. Data on gender, skin color (white and non-white), education (no schooling, incomplete or complete elementary education; high school; incomplete and complete higher education) and origin of referral (SUS and non-SUS) were analyzed by multiple logistic regression (p<0.05). Higher referral rates by the SUS were observed in 2017 (OR=1.27; 95% CI=1.098-1.480) and 2018 (OR=1.28; 95% CI=1.101-1.490); no differences were found between the years 2016 and 2019. Regarding gender, men were 40% more likely to have the SUS as the source of referral (OR=1.40; 95% CI=1.233-1.600). Non-white individuals were 34% more likely to have the SUS as the source of the referral (OR=1.34; 95% CI=1.190-1.512). Illiterate individuals or individuals who only attended elementary school were 6.38 times more likely to be referred by the SUS than individuals with higher education (OR=6.38; 95% CI=5.228-7.796). It is concluded that the origin of hospital referrals via SUS of patients with oral cancer is associated with socioeconomic factors.