Objective: To investigate weight concerns among adolescent boys and relationships with health indicators and family factors.Design: Analysis of the 2010 Health Behaviour in School-aged Children survey of 10-17-year-olds.Setting: Schools in the Republic of Ireland.Results: Among 6187 boys, 25.1 % reported a desire to lose weight (weight 'loss' concern) and 7.7 % reported a desire to gain weight (weight 'gain' concern). Both types of weight concerns were associated with poor self-rated health, life satisfaction and happiness, and with more frequent emotional and physical symptoms. Family factors were associated with boys' weight concerns. In adjusted analyses, the risk of weight 'loss' concerns decreased with daily family breakfasts (OR= 0.80; 95 % CI 0.66, 0.97). The risk of weight 'gain' concerns decreased with frequent family evening meals (OR= 0.77; 95 % CI 0.60, 0.99). Ease of communication with mother was associated with a decreased risk of weight 'loss' and weight 'gain' concerns among boys (OR= 0.74; 95 % CI 0.60, 0.90 and OR= 0.61; 95 % CI 0.44, 0.82, respectively). An open father-son relationship and having a father present in the home decreased the risk of weight 'loss' concerns (OR= 0.69; 95 % CI 0.57, 0.82 and OR= 0.81; 95 % CI 0.67, 0.98, respectively).Conclusions: Body weight concerns were reported by a sizeable minority of boys and were associated with negative health outcomes. The findings support the need to promote frequent family meals and facilitate open communication in families.