OBJECTIVES: With over one-third of the population considered to be obese, obesity has reached epidemic proportions in the U.S. The direct costs associated with obesity are currently estimated at about $238 billion. As the underlying cause of various chronic diseases, obesity negatively impacts quality of life due to impaired physical and mental well being and reduced daily functions. The objective of this study is to evaluate the relationship between obesity and health-related quality of life using the Centers for Disease Control and Prevention's (CDC) Behavioral Risk Factor Surveillance System (BRFSS) data. METHODS: The BRFSS is an ongoing, state-based, random digit dialed telephone survey of the civilian, non-institutionalized population aged ³ 18 years conducted by CDC. Data from sixteen states that collected information on health status (4 items), HRQoL (10 items), and demographic characteristics including weight and height from 50,454 participants in 1998 were utilized for the analysis. Participants who had a Body Mass Index (BMI) ³ 30 were defined as obese. Prevalence of obesity by demographics and disease presence was determined, as were corresponding HRQoL scores. RESULTS: On the basis of BMI, 31.9% of the respondents were identified as obese. Obesity was higher in males as compared to females and higher among African-Amercians and Hispanics as compared to whites. Obesity increased with age but decreased as income and education increased. Obese respondents reported poorer health status. Impact of obesity on HRQoL due to reduced physical and mental functioning in the presence of no health problems, as well as in presence of self-reported major health problems such as arthritis, cardiovascular disease, diabetes, cancer, depression, and pulmonary disease is discussed. CONCLUSIONS: Health related quality of life is significantly affected due to obesity and should be an important consideration in the treatment of obesity. It also has important implications in case of illnesses that have obesity as an underlying cause.