Key PointsQuestionAre younger patients admitted to the hospital for all-terrain vehicle (ATV)–related injuries more likely to experience worse injuries and more likely to die compared with older patients?FindingsIn this cross-sectional study using a large administrative health database that included 52 745 patients hospitalized with ATV-related injuries between 2002 and 2019, older adolescents and adults, particularly male patients, were more likely to die or experience a spinal cord injury or severe trauma.MeaningThis study’s findings suggest that patients aged 16 to 20 years, particularly male individuals, admitted to the hospital for an ATV-related injury tend to present with more severe injuries and are more likely to die than younger patients.