Abstract Background Bicycle-related head injury is an important public health issue. A paucity of statistical data on bicycle accidents exists in Taiwan. The purpose of this study was to report the characteristics of bicycle-related head injuries among school-aged children in Taipei, Taiwan. Methods Between 2001 and 2002, basic patient information of those with bicycle-related head injuries was collected from the Trauma Data Registry in 5 hospitals of the Taipei area. Telephone interviews were conducted to collect specific information surrounding bicycle accidents. Results Of 324 patients with bicycle-related head injuries, 90 (27.8%) had severe head injuries. Boys compared with girls had a higher proportion of severe head injuries (34.1% vs 23.4%; P = .048). Children aged 5 to 9 years had a higher proportion of severe head injuries compared with ages 10 to 14 years (65.2% vs 6.4%; P = .043). Bicycles without reflectors had a higher proportion of severe head injuries compared to bicycles with reflectors (69.0% vs 5.7%; P = .004). Bicyclists carrying goods (such as backpacks or weighted toward the road) and speeding were associated with severe head injury ( P < .05). Collisions with vehicles of a larger size resulted in a higher rate of severe head injury compared with collisions with pedestrians (76.9% vs 3.6%; P = .043). Conclusions For children whose main mode of transport is bicycles, the enforcement of helmet legislation, educational programs in bicycling safety and equipment, and improving the infrastructure for bicycling in urban areas are needed in Taiwan to reduce potentially debilitating or life-threatening injuries.