Objective: Little information exists that examines the epidemiology of injuries among adults who engage in sports and recreational activities. The purpose of this study is to examine basketball-related injuries among adults presenting to ambulatory settings in the United States. Design: Retrospective review of medical records. Setting: Emergency departments, outpatient departments, and physicians' offices in the United States. Patients: Nationally representative sample-of adults presenting to ambulatory care settings in the United States for treatment of injuries incurred while playing basketball. Main Outcome Measures: Body site injured, type of injury, ambulatory treatment site, and utilization of diagnostic testing. Results: An annual average of 507,000 adults were treated in an ambulatory care setting for injuries related to playing basketball. The majority of these patients sought treatment in physicians' offices. Females had a much lower rate of visits (0.8/1000) for basketball-related injuries than males (5.7/1000); African American males had a rate 2.7 times higher than white males. The most common injuries were sprains and strains to the lower leg and/or ankle region and fractures of the hand, wrist, or fingers. Specific analyses of patients presenting to the emergency department diagnosed with sprain/strain injuries to the lower leg/ankle region revealed that 93% of these patients received an x-ray procedure. Conclusions: Basketball injuries constitute a significant portion of ambulatory medical care use in the United States each year, particularly among young adult males and African American males. Better surveillance of adult participation in sports and recreational activities is needed to better identify risk and protective factors for injuries.