We studied pediatric bicycle accident victims (age ≤ 15 years) who were treated at our pediatric Level I trauma center during a 10-year period. Demographic data, injury severity, hospital course, and hospital cost data were collected. We compared the children who were helmeted to those who were unhelmeted. Our study cohort consisted of 516 patients. Patients were mostly male (70.2%) and white (84.7%); the median age was nine years. There were 101 children in the helmet group and 415 children in the unhelmeted group. Helmeted children were more likely to have private insurance (68.3% vs 35.9%, P < 0.001). Unhelmeted children were more likely to sustain multiple injuries (40% vs 25.7%, P = 0.008), meet our trauma activation criteria (45.5% vs 16.8%, P < 0.001), and be admitted to the hospital (42.4% vs 14.9%, P < 0.001). Helmeted children were less likely to sustain brain injuries (15.8% vs 25.8%, P = 0.037), skull fractures (1% vs 10.8%, P = 0.001), and facial fractures (1% vs 6%, P = 0.040). Median hospital costs were more expensive in the unhelmeted group. Helmet usage was suboptimal. Although most children sustained relatively minor injuries, the unhelmeted children had more injuries and higher costs than those who used helmets. Injury prevention programs are warranted.