Background The 2013 Children's Dental Health Survey is the fifth in a series of national surveys.Aim To describe the oral health behaviours in children and adolescents in England, Wales and Northern Ireland.Method A representative sample of children (aged 5, 8 12 and 15 years) in England, Wales and Northern Ireland were invited to participate in dental examinations. Children and parents were also invited to complete a questionnaire about oral health behaviours.Results Overall, the majority of children and young people reported good oral health behaviours. For example, more than three quarters of the 12- and 15-year-olds reported brushing their teeth twice a day or more often. However, a sizeable proportion of the sample reported less positive behaviours. Nearly 30% of 5-year-olds first started to brush their teeth after the age of one year. Among 15-year-olds, 11% were current smokers and 37% reported that they currently drank alcohol. Sixteen percent of 12-year-olds reported to consume drinks containing sugar four or more times a day. Of particular concern was the marked differences that existed by level of deprivation. Children living in lower income households (eligible for free school meals) were less likely to brush their teeth twice a day, more likely to start brushing after six months, more likely to be a smoker and more likely to consume frequent amounts of sugary drinks.Conclusion Despite some encouraging overall patterns of good oral health behaviours, a sizeable proportion of children and young people reported behaviours that may lead to poorer oral and general health. Preventive support should be delivered in clinical dental settings to encourage positive oral health behaviours. Public health strategies are also needed to reduce inequalities in oral health behaviours among children and young people.