Background: Oral diseases, particularly dental caries, affect as much as 9 in 10 persons globally. Its development starts during childhood and among factors participating in its aetiology, behavioural ones play a particularly important role. The aim of the study was to examine the selected behavioural risk factors of dental caries in Slovak adolescents between 2006 and 2018. Methods: We analysed occurrence of the selected factors (teeth brushing less than once a day, eating sweets and drinking sweetened soft drinks daily and their combination) in 11 to 13 years old schoolchildren in Slovakia by gender and socio-economic status using data from Health Behaviour in School-Aged Children surveys carried out in 2005/2006, 2009/2010, 2013/2014 and 2017/2018. Results: Consumption of sweets and sweetened soft drinks, despite of decline, remains widespread (41.3% of boys and 39.6% of girls in 2017/2018). Absence of daily teeth brushing, similarly as co-occurrence of these two risk factors, were more frequent in boys (10.6% and 5.0% in 2017/2018, respectively) than in girls (5.1% and 2.3% in 2017/2018, respectively). Absence of daily teeth brushing was associated with lower socioeconomic situation. Conclusions: Behavioural risk factors of dental caries play significant role in oral health of adolescents in Slovakia. Despite positive development of the epidemiological situation, effective interventions focused on consumption of sweets and sweetened soft drinks as well as improvement of oral hygiene in lower socioeconomic groups are needed.