Aim: To assess the knowledge and attitude of undergraduate dental students about oral cancer. Methods: A cross-sectional, quantitative study was conducted based on a questionnaire containing 15 questions about prevention, clinical aspects, and attitudes towards oral cancer. One hundredthirty-three undergraduate dental students between the second and fifth years were enrolled. The statistical significance was measured by Pearson's chi-square test. Results: There was a predominance of females (58.65%) and most students were between 20 and 30 years of age (75.19%). The risk factors for oral cancer mainly described by the students were smoking (92.48%) and drinking (84.21%). Squamous cell carcinoma was described as the most common type of oral cancer by 48.12% of the students. As much as 53.38% of the participants considered the tongue as the most affected anatomic region, 57.89% reported ulcers as the most frequent clinical aspect, and 44.36% attributed a firm and painless aspect to the regional metastatic lymph nodes. Most students reported regularly conducting a thorough examination of the oral cavity (81.95%). Two of the 15 variables showed differences between the students, according to the school time: previous head and neck carcinoma (Pearson's chi-square, p = 0.03) and guidance on the discontinuation of harmful habits (Pearson's chi-square, p = 0.02). Conclusions: Students have a good knowledge of the etiology of oral cancer and are apparently alert in their examinations. The clinical aspects of the oral carcinoma, however, are not so clear. The difference regarding knowledge and attitudes towards oral cancer was minimal when different undergraduate years were considered. It is necessary to implement the clinical suspicion of oral cancer throughout the undergraduate course to enable awareness and early diagnosis.