The objective of this study was to examine injury risk in children with autism, ADD/ADD, learning disability, psychopathology, or other medical conditions. Children aged 3-5 years who participated in the National Survey of Children's Health were included. Six study groups were analyzed in this report: autism (n=82), ADD/ADHD (n=191), learning disability (n=307), psychopathology (n=210), other medical conditions (n=1802), and unaffected controls (n=13,398). The weighted prevalence of injury in each group was 24.2% (autism), 26.5% (ADD/ADHD), 9.3% (learning disability), 20.5% (psychopathology), 14.6% (other medical conditions), and 11.9% (unaffected controls). Compared to unaffected controls, the risk of injury was 2.15 (95% confidence interval (CI): 1.00-4.60), 2.74 (95% CI: 1.63-4.59), 2.06 (95% CI: 1.24-3.42), and 1.26 (95% CI: 1.00-1.58) in children with autism, ADD/ADHD, psychopathology, and other medical conditions, respectively, after adjusting for child sex, child age, number of children in the household, child race, and family poverty level. Children with autism, ADD/ADHD, and other psychopathology were about 2-3 times more likely to experience an injury that needs medical attention than unaffected controls. Future studies need to clarify the extent to which injuries in young children with autism, ADD/ADHD, and psychopathology are related to core symptoms, comorbid conditions, associated behaviors, or unintentional injuries due to lack of additional supervision from caregivers. (Contains 3 tables.)