Gastroesophageal reflux is a potential trigger of asthma that may be clinically silent. This study examines the prevalence of gastroesophageal reflux in asthma patients without reflux symptoms. This prospective cohort study evaluated 26 patients with stable asthma without reflux symptoms using esophageal manometry and 24-h esophageal pH testing. Gastroesophageal reflux was considered present if esophageal acid contact times were abnormal. Demographic variables were analyzed to determine if they predicted the presence of gastroesophageal reflux. Asthma patients with asymptomatic gastroesophageal reflux were compared with 30 age-matched asthma patients with symptomatic gastroesophageal reflux. The prevalence of abnormal 24-h esophageal pH tests in asthma patients without reflux symptoms was 62% (16 of 26). Demographic variables did not predict abnormal 24-h esophageal pH tests in asthma patients with asymptomatic gastroesophageal reflux. Asthma patients with asymptomatic gastroesophageal reflux had higher amounts of proximal esophageal acid exposure (p < 0.05) compared with asthma patients with symptomatic gastroesophageal reflux. Because demographic variables do not predict abnormal 24-h esophageal pH tests in asthma patients without reflux symptoms, 24-h esophageal pH testing is required. This study suggests that gastroesophageal reflux is present in asthma patients, even in the absence of esophageal symptoms.