Mechanism of injury (MOI) varies by population characteristics, influences the nature of resultant injury, and the probability of care in a trauma center. We analyzed 103,719 trauma discharges from New York City hospitals between 1999 and 2001 from the New York State SPARCS database. MOI (E-codes) for each discharge were aggregated into relevant MOI groups (Assault, Falls, Firearm, Knife/Penetrating, Motor Vehicle Accidents (MVA), and Other). Each discharge DRG was aggregated into a clinical injury class (CNS, General/GI, Cardiothoracic (CT), Genitourinary (GU), Orthopedic (Ortho), and Vascular). We analyzed age and gender characteristics, using an RDRG-derived 4-toer severity of illness index as a mortality risk surrogate, and distribution to trauma centers (TC) versus non-TC. Age and gender distributions for each MOI demonstrated a predominance of young males for each MOI except Falls, where elderly females predominated. Falls were most likely to produce orthopedic injuries (75.6%) and were responsible for 65.5% of all orthopedic injuries and 40.5% of all CNS injuries. Only MVAs produced a comparable proportion of CNS injuries (30.6%). Fall MOI produced the most high severity (Severity Index 3) injuries. TCs discharged only 35.6% of fall victims. MOI varies among age and gender groups and produces different types of injuries. MOI powerfully influences injured patients' distribution to TC and non-TCs. Despite the high risk of elderly female fall victims, triage systems do not distribute these patients to TCs, in favor of lower risk MOIs.TABLE-ABSTRACT P100MOIAge (mean)MalesInjury classSeverity3TCCNSOrthoGen/GIAssault31.183.7%17.8%3.8%31.3%15.1%68.0%Fall59 .940.0%40.5%65.6%19.9%48.2%35.6%Firearm28.690.7%0.4%0.3%2.0%0.7%59.7%Knife31 .885.4%2.5%1.5%5.5%2.7%56.1%MVA37.365.2%30.6%14.9%20.7%18.2%69.4%Other38.765 .3%8.1%13.9%20.4%15.2%41.2%*Fall versus others, t-test P < 0.001;**chi-square, P < 0.001.