A total of 7185 faecal specimens collected from infants and children with gastroenteritis in seven different regions of Japan during 1995-2009 were examined for adenovirus by polymerase chain reaction. Adenovirus was detected in 568 (7.9%) patients. The adenovirus activity peak was in winter and spring seasons (December-March) during the study period in the Japanese paediatric population. During the last 15 years, adenovirus 41 was the most predominant strain in Japan.