Objective. The purpose of this study was to assess whether cocaine-related trauma is underreported to the US Federal Drug Abuse Warning Network (DAWN). Methods. We compared DAWN reports filed by an urban emergency department with the department's toxicology results for patients treated for major trauma. DAWN regulations in effect during the study period required the reporting of all patients treated for injury who used drugs or who tested positive for drugs of abuse. Results. Of 520 patients treated for major trauma, 217 (42%) were tested for a variety of drugs. Of these, 82 (38%) tested positive for cocaine. Of the 102 patients injured in motor vehicle accidents, 20 (20%) tested positive for cocaine. Of the 59 patients injured in motor vehicle accidents who were under age 40, 18 (30%) tested positive for cocaine. Of 100 victims of violent assault, 57 tested positive for cocame. During the time period studied, DAWN recorded 48 hospital visits associated with cocaine, none involving trauma or injury. Conclusions. Cocaine-related trauma was unreported to DAWN despite the hospital's compliance with the system's guidelines. The pattern of DAWN reports from other institutions suggests that underreporting of cocaine-related injury is widespread.