The comorbidity between schizophrenia and cannabis addiction is a real public health problem, which is not without consequences on the clinical presentation of patients and the evolution of the disease. Current research is directed towards the study of brain mechanisms and structures that are common to both diseases, including those involving the endo-cannabinoid system. Cannabis sativa indica is a plant rich in psychoactive principles, of which Δ9 tetrahydrocannabinol is the most active. All studies show that long-term cannabis aggravates schizophrenia and that cannabis precipitates schizophrenia either through interaction between genetic and environmental factors or by disrupting brain development. Consequences: Higher and longer rates of hospitalization. The increase in the frequency of crime and suicide. Acceleration of the evolutionary short with more brutal decompensations, earlier. Less compliance with treatments. More social disintegration. Greater frequency of relapses for both disorders. Significant socio-economic weight