BACKGROUND Gastroesophageal reflux disease (GERD) is a common comorbidity among patients with asthma. In addition, functional dyspepsia (FD) is characterized by upper abdominal symptoms without organic disease manifestations. However, the prevalence of FD among patients with asthma remains uninvestigated; therefore, herein, we investigated the prevalence of dyspepsia symptoms in these patients. METHODS We recruited 156 patients with asthma from the outpatient clinic of Teikyo University Hospital and investigated the prevalence of dyspepsia symptoms using the modified Frequency Scale for the Symptoms of GERD. Further, the relationship between dyspepsia symptoms and clinical background of asthma was also investigated. RESULTS Certain digestive organ symptoms were exhibited by 83% of patients with asthma, dyspepsia symptoms by 44%, and reflux symptoms by 26%. The dyspepsia-dominant group showed significantly higher female ratio and numerically lower %FEV1 than the asymptomatic group. In the group with dyspepsia score >5 points, the ratio of patients undergoing step 4 asthma treatment and the ratio of those using long-acting muscarinic receptor antagonist were higher than those in the group with a score <5 points. Furthermore, endoscopic diagnosis was also made in 84 patients and the prevalence of FD was 21%. CONCLUSIONS A considerable proportion of patients with asthma exhibited dyspepsia symptoms, and the asthma severity in patients with dyspepsia was higher than those in asymptomatic patients. Based on the current findings, more attention should be directed to FD, in addition to GERD, as a comorbidity of the digestive system in patients with asthma.