The effect of viewing a humorous film on bronchial responsiveness to methacholine [methacholine study: 20 healthy participants and 20 patients with house dust mite (HDM)-allergic bronchial asthma (BA)] or to epigallocatechin gallate (EGCg; EGCg study: 15 normal participants and 15 EGCg-allergic BA patients) was studied. At baseline, bronchial challenge test to methacholine (20 normal participants and 20 HDM-allergic BA patients) or EGCg (15 normal participants and 15 EGCg-allergic BA patients) were performed. After 2 weeks, patients and healthy participants were randomly assigned to watch a humorous or a nonhumorous film. Two weeks later, the alternate film was watched. Immediately after viewing, bronchial challenge test to methacholine or ECGg to each study group were performed. Viewing a humorous film significantly reduced bronchial responsiveness to methacholine or EGCg, while viewing a nonhumorous film failed to do so in BA patients without affecting bronchial responsiveness to methacholine or EGCg in healthy participants. These findings indicate that viewing a humorous film may be useful in the treatment and study of BA.