The drug dependence especially opioid dependence, represents at moment a very challenging therapeutic domain, even that huge steps-methadone, buprenorphine, naltrexone-had been discovered.

The fact that almost 50% of all drug-induced psychosis results during the progess of disease to various forms of schizophrenia is as well an undeniable truth.

The main aim of this retrospective study is to raise the question, upon a possible therapeutic effect of methadone in the clinical evolution of patients diagnosed according with DSMIV with clinical forms of Schizophrenia Sdr which are presenting as well a drug dependence sdr.

The study had been realised on patients which were held in various prison establishments. the number of the patients was 24 with age between 24-35 years old, with longstanding history of heroin of heroin abuse(IV user) for tlast 10 years, cocaine/crack user-10 years,10 years of cannabis user.

All patients were presenting at the start of the stydy positive symptoms(delusion with presecutory themes; auditive and viusal hallucinations; evident thought disorders) and negative symptoms (apathy, anhedonia, social isolation, even at the point of autistic withdrawal). All of them were under specific treatment with second generation of antipsychotics-e.g. Olanzapine, Risperidone, Aripiprazole.

The length of time for the study was of 9 months. During this interval, after they had re start the methadone programme with corect adjusted doses depending on the severity of their drug dependence, it had been seen a massive reduction of negative symptoms but also a semnificative decrease of their positive symptoms-especially hallucinations.

The main explanation for this unexpected therapeutic effect is represented by the mechanisms which oipiod substitutes-methadone, esp-exerts upon the dopaminergic pathways (involved in the genesis of schizophrenic pathology).