We determined the prevalence of gastroesophageal reflux disease (GERD) symptoms and the associations between GERD symptoms and asthma morbidity in a population of adolescents with asthma. Two thousand, three hundred and ninety-seven students attending six middle schools in Seattle completed the International Study of Asthma and Allergy in Children (ISAAC) written and video survey that included additional questions pertaining to GERD symptoms and asthma morbidity. Based on their responses, children were categorized as having undiagnosed current asthma, physician-diagnosed current asthma, or no asthma symptoms. The prevalence of GERD symptoms occurring at least weekly or daily was determined for each group. The asthma morbidity outcomes were emergency department visits, physician visits, missed school days, and use of inhaled medications for respiratory symptoms within the past year. Associations between GERD symptoms and asthma morbidity outcomes were determined using logistic regression. The prevalence of GERD symptoms was significantly higher among students with current asthma (19.3%; 95% confidence interval (CI), 14.9-24.2) than students with no asthma symptoms (2.5%; 95% CI, 1.8-3.4). In children with current asthma (n = 296), symptoms of GERD that occurred at least weekly were strongly associated with emergency department visits (odds ratio (OR), 5.0; 95% CI, 2.6-9.6), physician visits (OR, 2.5; 95% CI, 1.3-4.6), missed school (OR, 2.0; 95% CI, 1.1-3.7), and inhaled medication use (OR, 2.5; 95% CI, 1.3-4.7). The associations between GERD symptoms and emergency department visits, physician visits, and inhaled medication use were stronger among children with asthma who reported daily GERD symptoms (n = 14) than among children reporting weekly GERD symptoms (n = 57). The prevalence of GERD symptoms was greater in adolescents with current asthma than in those without asthma. In addition, the presence of at least weekly GERD symptoms was strongly associated with greater asthma morbidity and the use of asthma medications.