Introduction. This study is a long-term follow-up of an early replication of the Peniston EEG biofeedback (EEG-BFB) Protocol for chemical dependency (Peniston & Kulkosky, 1989, 1990).Method. This clinical trial included 16 chemically dependent adult participants treated with the Peniston Protocol in a university outpatient clinic between 1993 and 1995. Ten participants were probationers classified as high risk for rearrest. Treatment effects were assessed using pre/posttreatment measures (Beck Depression Inventory, Minnesota Multiphasic Personality Inventory-2) and long-term follow-up of abstinence and rearrest rates. Probationer rearrest rates were compared to an equivalent probation sample (n = 24) that did not receive EEG-BFB.Results. Initial Beck Depression Inventory scores indicated mild/moderate depression but were significantly reduced posttreatment to within normal limits. Substantial differences were noted posttreatment on 7 Minnesota Multiphasic Personality Inventory-2 clinical scales suggesting less psychopathology following treatment. Long-term (74–98 months) follow-up indicated that 81.3% (n = 13) participants were abstinent. Rearrest rates and probation revocations for the probationer subgroup were lower than the comparison group (40% vs. 79.16%).Conclusion. This study provides evidence of the durability of Peniston Protocol results over time but has the usual limitations of a clinical trial with a small sample, nonrandomized, and uncontrolled design. Implications for further research are discussed including the relevance of recent modifications to the Peniston Protocol and qEEG–based protocols in treating substance abuse.