 Tardive dyskinesia is a common complication of conventional antipsychotic treatment in subjects with schizophrenia. This study investigates whether the addition of the omega-3 fatty acid, ethyl-eicosapentaenoic acid EPA to usual treatment improves movement disorder in 84 schizophrenia subjects with established tardive dyskinesia. The initial double-blinded, randomised trial duration is 12 weeks, followed by further 46 weeks of open-label treatment. 