The treatment of dual disorders suppose a real challenge for the psychians implied with these kind of patients. The prevalence of these disorders are increasing due to the high level of disponibility of drug in the currents moment. One of the theory which try to explain the reasons why these patients use drug is the self medication hypothesis: the use of the drug relieve some distress provocated by the disorder of the psychopharmacological treatment, leading in both cases to refuse the treatment, leading to a increase of the symptoms and a worse prognosis. In this book, the authors have tried to understand the biochemical mechanism involved in this disease, with the intention to find some psychopharmacological approach. After that, we make a review of the literature about which treatment (even psychological) have shown some efficiency. In the last chapter, we show the results of a preliminary study carried out in Spain, with some promising data with the use of Long-acting antipsychotic. Our intention is to induce the realization of more studies in this field, with a lager samples, to confirm our previous data and help the people involved in the treatment of these patients.