This study examined the relations between family structure and students' health-related behaviors. Participants were 6,130 Greek students, ages 11 to 16 years. They responded to questionnaires based on the Planned Behavior model assessing attitudes, perceived behavioral control, intentions and behavior regarding healthy and unhealthy habits. Students who reported growing up with one or no parent reported more unhealthy lifestyle attitudes and behaviors (smoking, drug use, violence, exercise, nutrition) than students growing up with both parents. The findings suggest that family structure is related to students' healthy or unhealthy lifestyle, indicating that in health education programs all members of the close environment within which the children live should be involved, especially for children who do not live with both parents.