IntroductionThe positive attitude and behaviour of dental students can be improved during their undergraduate studies and is considered an essential factor in promoting the oral self-care habits of their patients and society in general.AimThis study was conducted to evaluate the oral health knowledge, attitudes and behaviours among undergraduate dental students at a private university, based on the year of undergraduate studies.Material and methodsA self-administered questionnaire based on the Hiroshima University-Dental Behavioural Inventory was distributed among 783 undergraduate dental students from 1st to 5th year. Statistical analysis was performed using SPSS version 20. The Mann–Whitney U test and one-way ANOVA tests (Kruskal–Wallis test) were used.ResultsThe scores of oral health knowledge, attitude and behaviour between preclinical and clinical dental students were found to have statistically significant differences (P < 0.001). The variation of knowledge, attitude and behaviour scores from 1st to 5th year undergraduate studies was shown to be statistically significant with the year of study (P < 0.001). The study showed significant improvement in the knowledge, attitude and behaviour of the final year dental students as compared with the 1st year dental students.ConclusionPreclinical students need properly designed oral health educational programs to increase their attitude and behaviour toward oral health.