This study compared the frequency and types of dissociative experiences reported by detoxified alcoholics and drug abusers, and examined the relationship between dissociation and recent and lifetime use of alcohol, cannabis, cocaine, and heroin. One hundred thirty-eight self-referred male veterans detoxified from alcohol (N=62) and drugs (N=76) on inpatient units at a Veterans Affairs hospital completed questionnaires including the Dissociative Experiences Scale. Three types of dissociative experiences were examined: amnesia, depersonalization/derealization, and absorption. Ninety-one of the patients were also given the Addiction Severity Index interview to determine their histories of recent (past 30 days) and lifetime drug and alcohol use. High levels of dissociation were found in both groups, with alcoholics reporting higher levels of all three types of dissociative experiences than drug addicts. Chronicity (lifetime years) of both alcohol and cocaine use was significantly correlated with dissociation scores. The amnestic effect of chronic cocaine use persisted even after controlling for the effects of chronic alcohol use. In contrast, no dissociative effects of recent (past month) use of alcohol or drugs were found. These findings suggest that dissociation may be a chronic residual effect of long-term substance abuse, including both alcohol and cocaine. Implications are discussed for the treatment of chronic substance abusers.