Objective: To assess risk factors for injury among children and adolescents treated with stimulants for ADHD. Method: An analysis was performed of pharmacy and service claims data from 2000-2003 California Medicaid (Medi-Cal) focusing on children and adolescents ages 6 to 17 years who initiated stimulant therapy for ADHD. Bivariate and multivariate analyses were performed to examine associations of demographic and clinical characteristics with injury. Results: In a Cox proportional hazard model that controlled for background patient characteristics, patients ages 13 to 17 years, male gender, prescription of anxiolytic/hypnotic medications, and diagnosis of a mood disorder were each independently associated with increased risk of injury, whereas African American ancestry and other minority racial/ethnic ancestry were associated with lower risk. Youth with high stimulant medication possession ratios (MPR) had a nonsignificantly lower risk of injury as compared to those with a low stimulant MPR. Conclusion: These findings reveal several patient characteristics that may be associated with increased risk of injury among children and adolescents treated for ADHD. (Contains 2 tables.)