This article reviews the results of a retrospective study of all patients with a firearm-related injury who were admitted to the University of California, Davis, Medical Center between January 1, 1990, and December 31, 1992. The foci of the study were hospital inpatient charges, costs, revenues, and net income, according to payer source. Patients who were treated for firearm- related injuries in the emergency department and who expired in or were discharged to home from the emergency department were not included in the study. Information from the trauma registry and hospital finance records were linked for 750 out of a total of 787 consecutive patients admitted to the hospital for firearm-related injuries. The analysis of the data indicates that although a substantial majority, i.e., 70 percent, of the patients with firearm-related injuries did not have private health insurance, the treatment of firearm- related injuries produces net income for this particular university trauma center by virtue of the cost shifting built into its pricing structure. If data from this institution are extrapolated to the Nation, then the actual cost of providing medical care for firearm-related injuries in the United States in 1995 is projected to be $4.0 billion, the majority of which cost will be paid directly by private health insurance. Tables, references