Aim of this work is to show the association between insecure attachment pattern and drug or alcohol addiction development in a population of four therapeutic facilities inpatients. Particularly disorganized attachment is postulated being the most frequent internal working model, nonetheless poorly investigated by literature about substance use disorder. Attachment disorganization causes a lack of coping strategies and a vulnerability for depersonalization state of mind or other dissociative symptoms. The addiction substances or alcohol dopaminergic effect may deactivate the attachment system, preventing the depersonalization experience. Separation Anxiety Test (SAT) was administered to ascertain attachment patterns. Results show that disorganized attachment clearly prevail over ambivalent, avoidant and secure patterns. No appreciable differences between alcohol and drug addicted samples is noticed.