Objectives: Wearing a helmet while riding a motorcycle is compulsory in Taiwan. The main objectives of current study are to understand the helmet wearing undertaken by children aged 6 to 12 while riding on a motorcycle, and to investigate their variations among geographic locations and family aggregation. Methods: The data used in this study is part of the 2001 National Health Interview Survey. 1,787 children who were aged 6 to 12 and had the experience of riding on motorcycle were taken into analysis. Items in questionnaire for children under 12 years old were used. They were also linked to a questionnaire for adults older than 12 years in the same household. Results: 78.9% of children reported always wearing a helmet while riding on a motorcycle. Logistic regression was applied to investigate the factors associated with helmet use. It is found that the following characteristics are associated with helmet wearing: older age, residing in the northern (the metropolitian Taipei, Kee-Lung and Taipei County, the counties of Tao-Yuan, Hsin-Chu and Miao-Li), central (Tai-Chung, Chang-Hwa, Nan-Tou) and eastern (the counties of I-Lan, Huan-Lien and Tai-Tung) of the island, and other family members wearing helmets. Conclusions: There is geographic variation in wearing helmets. Whether children always wear a helmet is also significantly associated with other family member's helmet wearing.