Authors refer on the results of the HBSC study monitoring behavioural components of health in a repre-sentative sample of Czech children aged from 11 to 15 years. They focus on the relation between family structure and the development of certain health endangering habits. Out of the followed sample of 5 012 children 72,9 % were growing up in a complete family; 13,6 % in an incomplete family; 11,7 % with one biological and one step parent (so-called complemented family) and 1,8 % without parents. The children living in complete families showed relatively less health endangering habits. In comparison with other children they more often stated that they eat their meals together with another family member, they less often skipped one of the main meals, they had more physical activities, they engaged in sports with their parents more often and they less frequently smoked cigarettes, drank alcohol and had lower experience with marijuana. The results of the study document that a loss of one parent represents a risk factor in the deve¬lopment of a chilďs life style. In the context of the sample which was studied, the family manifested itself as a complex factor, in which the family atmosphere and the education of parents had also an important role. In comparison with the families with one step parent, incomplete families surprisingly demonstrated more shared activities and higher control over certain risk habits of the children.

        Key words: family structure, incomplete family, life style, eating habits, physical activity, habitual risks