Adolescent health behaviours are influenced by a variety of social factors, including social orientations, such as social comparison or competitiveness. The main goal of the present study was to investigate the role that these social orientations might play in health behaviours (both health-impairing and health-promoting). Data were collected from high school students (N=548; ages 14-20 years; 39.9% males) in two counties of the Southern Plain Region of Hungary. The self-administered questionnaires contained items on sociodemographics, such as age, sex, parental schooling, and socioeconomic status (SES) self-assessment; school achievement, health behaviours, competitiveness and social comparison. Multiple regression analyses suggest that those who scored higher on competitiveness engaged in more substance use, a pattern that was not present for health-promoting behaviours. Social comparison, however, was associated with lower levels of substance use. In addition, in relation to health-impairing behaviours, both competitiveness and social comparison interacted with sex; both social orientation variables proved to be more important for boys. Social comparison also contributed to health-promoting behaviours among boys. Findings support the idea that the role of social orientations, such as competitiveness and social comparison, can be quite different depending on sex and the nature of the health behaviour. While competitiveness may act as a risk factor for substance use among boys, social comparison may act as a protection. It appears that social orientations play less of a role in girls' health-related behaviours. More focus is needed on gender differences in influences on adolescents' health-related behaviours.