BACKGROUND: We investigated the incidences and age-related/seasonal variations of respiratory virus infections in a regional area in Korea. METHODS: A total of 3,467 respiratory specimens from patients with acute respiratory infection symptoms in a teaching hospital were tested for respiratory viruses during 2013 - 2015. RESULTS: At least one virus was detected in 2,561 of the 3,467 specimens (73.9%), and 706 patients (20.4%) were positive for two or more viruses. The most frequently detected viruses were rhinovirus (23.9%), respiratory syncytial virus B (15.5%), and adenovirus (12.5%). Most of the patients (with and without a detected virus) were children. Young children (< 5 years old) were significantly more likely to have two or more viruses compared to older individuals (p < 0.0001). Most viruses exhibited seasonal variations. CONCLUSIONS: This study revealed the incidence of respiratory virus infections. These findings can enhance our understanding of the distribution of respiratory viruses according to patient age and season.