The prevalence of obesity is increasing in America, but its impact on morbidity relative to other health risks is unclear. This paper compares the effects of overweight, poverty, smoking and problem drinking on occurrence of chronic conditions and health-related quality of life. The data were collected from a nationally representative household telephone survey of 9585 adults fielded in 1998, using self-reported measures of height and weight, poverty, smoking status, problem drinking, chronic conditions and SF-12 global scales. Regression analyses were used to estimate effects of health risk factors on morbidity. Thirty-six percent of adults are overweight but not obese (25< or =BMI<30) and another 23% are obese (BMI> or =30). Controlling for demographics, obesity is associated with more chronic conditions and worse physical health-related quality of life (P<0.01). Smoking history and poverty predict having chronic conditions, but their effect sizes are significantly smaller. Even after controlling for chronic conditions, obesity predicts physical health-related quality of life, in that case with an effect size similar to poverty. The effect of problem drinking is always smaller. Obesity is highly prevalent and associated with at least as much morbidity as are poverty, smoking and problem drinking. Nevertheless, the latter have achieved more consistent attention in recent decades in clinical practice and public health policy.