Objective: The aim of this study was to explore parental perceptions of adolescent health behaviours and to examine to what extent parents' perceptions of their children's health behaviours are determined by the family's socio-demographic characteristics. Method: Participants in the study were 605 parents. They completed questionnaires in which they rated whether different health-risk behaviours were present in their children (i.e. smoking, alcohol consumption, drug use, risky sexual behaviour, insufficient physical activity, unhealthy eating habits and obesity). Parents also provided information on the family's socio-demographic characteristics. Results: The results show that parents rate insufficient physical activity and unhealthy eating habits as the most pronounced problems in their children, while they rate risky sexual behaviour and drug use as the least pronounced. Parents estimate that insufficient physical activity and unhealthy eating habits are significantly more pronounced among girls than among boys. The results of factor analysis reveal that, from the parents' perspective, adolescent health-risk behaviours can be grouped into those pertaining to unhealthy habits and those connected to addictive and risk behaviours. Parents rate that behaviours reflecting unhealthy lifestyle are significantly more present among girls than among boys. Regression analyses showed that a family's living standard is the only significant predictor of unhealthy habits and addictive and risk behaviours. Conclusion: When observed from a parental perspective, adolescent health-risk behaviours can be grouped into different categories, and parents claim to observe certain differences in these behaviours between boys and girls. The most important determinant of adolescent health behaviours is a family's living standard.