One measure of a substance's addictive risk is the proportion of users who become dependent. This study evaluates the lifetime and current risk of substance dependence among lifetime substance users' among trauma inpatients and provides a relative ranking of addictive risk among the substances. Data on use of 8 substance groups (alcohol, opiates, marijuana, cocaine, other stimulants, sedative-hypnotics, hallucinogens, other drugs) were obtained by interview (Structured Clinical Interview for the DSM-III-R) from 1,118 adult trauma inpatients. Prevalence of lifetime dependence among lifetime users ranged from 80.7% for opiates and 70.9% for cocaine to 33.3% for hallucinogens and 26.6% for sedative-hypnotics. The rank order of addictive risk was similar to that found in the general population. Trauma inpatients had a higher absolute addictive risk than the general population, comparable to the risk found in patients in treatment for substance use disorders, suggesting the importance of screening trauma inpatients for substance dependence.