Background The association of obesity with asthma outcomes is not well understood. Objective The objective of this study was to examine the association of obesity, as represented by a body mass index (BMI) of greater than 30 kg/m2 , with quality-of-life scores, asthma control problems, and asthma-related hospitalizations. Methods The study followed a cross-sectional design. Questionnaires were completed at home by a random sample of 1113 members of a large integrated health care organization who were 35 years of age or older with health care use suggestive of active asthma. Outcomes included the mini-Asthma Quality of Life Questionnaire, the Asthma Therapy Assessment Questionnaire, and self-reported asthma-related hospitalization. Several other factors known to influence asthma outcomes also were collected: demographics, smoking status, oral corticosteroid use in the past month, evidence of gastroesophageal reflux disease, and inhaled corticosteroid use in the past month. Multiple logistic regression models were used to measure the association of BMI status with outcomes. Results Even after adjusting for demographics, smoking status, oral corticosteroid use, evidence of gastroesophageal reflux disease, and inhaled corticosteroid use, obese adults were more likely than those with normal BMIs (<25 kg/m2 ) to report poor asthma-specific quality of life (odds ratio OR, 2.8; 95% CI, 1.6-4.9), poor asthma control (OR, 2.7; 95% CI, 1.7-4.3), and a history of asthma-related hospitalizations (OR, 4.6; 95% CI, 1.4-14.4). Conclusions Our findings suggest that obesity is associated with worse asthma outcomes, especially an increased risk of asthma-related hospitalizations.