AbstractBackground:Considering the role of different ethnical, cultural and geographical factors in health related quality of life (HRQOL) as well as the perception of different populations regarding various weight disorders, we aimed to evaluate the association between body mass index (BMI) and HRQOL in Iranian children and adolescents.Methods:This cross-sectional study was part of the Weight Disorders Survey of the CASPIAN-IV study. During this study, students aged 6–18 years from urban and rural areas of 30 provinces of Iran were selected. HRQOL of the students was evaluated by using the Persian version of the Pediatric Quality of Life inventory (PedsQL™ 4.0™ 4.0) Generic Core Scales. The mean of total HRQOL and its subscales were compared in underweight, normal weight, overweight and obese students.Results:The mean of total HRQOL, physical functioning and psychological functioning scores in the total population were 83.31, 84.25 and 82.79, respectively. The mean of the total HRQOL score and the psychosocial score were significantly lower in underweight students aged 6–12 years than in other groups (p<0.05). The mean of the total HRQOL score and psychosocial score were significantly lower in obese students aged 13–18 years than in other groups (p<0.05). Overweight and obesity was negatively associated with total HRQOL, psychosocial and school functioning subscales (p<0.05). There was a significant negative association between emotional functioning and obesity (p<0.05).Conclusions:The findings or this study support the importance of personal perception and cultural norm roles in HRQOL. Given the association between weight disorders and psychosocial health, it is suggested that social and cultural factors have a more crucial role in the HRQOL of children and adolescents.