The relationship between schizophrenia and drug abuse has been approached using physiopathological, psychopathological, and cybernetics communicational techniques. The hypotheses which have been proposed with regard to the physiological mechanism involved in schizophrenia and drug abuse all have in common, among other things, the idea that neurotransmitters play a role in the development of these behaviors. Likewise, the psychopathological symptoms presented by schizophrenia and drug abuse offen many similarities. The mechanism by which drug abuse may lead to schizophrenia is discussed. The analysis of the communicational system reveals the correlation between there two syndroms. None of the three techniques which have been described should be exclused from clinical practice.