Oral diseases, particularly dental caries, affect as much as nine in 10 persons globally. Its development starts during childhood. Behavioural factors play an important role in its aetiology. The aim of the research was to analyse the prevalence of selected behavioural factors associated with dental caries in Slovak adolescents. Selected factors, such as toothbrushing less than once a day, consumption of sweets and sweetened soft drinks daily and their combination, were analysed using data from Health Behaviour in School-Aged Children surveys carried out in 2005/2006, 2009/2010, 2013/2014 and 2017/2018 in Slovakia. The target group consisted of 11- to 13-year-old schoolchildren. The results were analysed by sex and socioeconomic status. The consumption of sweets and sweetened soft drinks, despite declining, remains widespread (41.3% of boys and 39.6% of girls in 2017/2018). The absence of daily toothbrushing, similarly as a co-occurrence of 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). The absence of daily toothbrushing was associated with a lower socioeconomic situation. In conclusion, behavioural risk factors affecting oral health are widespread in Slovak adolescents. Despite the positive development of the epidemiological situation, effective interventions, as well as the improvement of oral hygiene in lower socioeconomic groups, are needed.