Using questionnaires for 281 healthy subjects and 139 asthmatic patients in 5 medical institutes, we investigated the relationship between the common cold and acute asthma. The frequency of the common cold, duration to recovery and absences from work were slightly higher in asthmatics than healthy subjects. Acute asthma occurred in a few days following common cold and subsided at the end of or after the common cold. Evaluation of the types of common cold revealed that the cold, which causes upper respiratory symptoms, frequently induced acute asthma. Bronchodilators seemed to be less effective for cold-induced asthma. Collectively, these results suggested that the common cold induces acute asthma not through virus-induced direct inflammatory responses but through indirect immunological responses. Through these questionnaires, we realized that it is important to prevent the common cold, a trigger of asthma attacks. As the guidelines of asthma therapy recommended, the use of corticosteroid must be considered when acute asthma attacks occur.