The present invention relates to the use of one or more cannabinoids in combination with one or more anti-psychotic medicaments for use in the prevention or treatment of psychosis and psychotic disorders. Preferably the one or more cannabinoids are taken from the group: cannabidiol (CBD); cannabidiolic acid (CBDA); tetrahydrocannbidivarin (THCV); tetrahydrocannbidivarinin acid (THCVA); cannabichromene (CBC); cannabichromenic acid (CBCA); cannabigerol (CBG) and cannabigerolic acid (CBGA). Preferably the anti-psychotic medication is an atypical anti-psychotic medication.