BACKGROUND: Tardive dyskinesia is a disfiguring movement disorder of the orofacial region often caused by antipsychotic drugs. A wide range of strategies has been used to help manage tardive dyskinesia and, for people who are unable to have their antipsychotic medication stopped or substantially changed, the calcium-channel blocking group of drugs (diltiazem, nifedipine, nimodipine, verapamil) has been suggested as a useful adjunctive treatment. OBJECTIVES: To determine the effects of calcium-channel blocker drugs (diltiazem, nifedipine, nimodipine, verapamil) for treatment of neuroleptic-induced tardive dyskinesia in people with schizophrenia, schizoaffective disorder or other chronic mental illnesses. SEARCH STRATEGY: We updated previous searches of the Cochrane Schizophrenia Group Register (1982-2000), Cochrane Library (Issue 4, 2000), Cochrane Schizophrenia Group's register of trials (November 2000), EMBASE (1980-2000), LILACS (1982-2000), MEDLINE (1966-2000), PsycLIT (1974-2000), and SCISEARCH by searching the Cochrane Schizophrenia Group Register (September 2003). We searched references of all identified studies for further trial citations and contacted authors of trials. SELECTION CRITERIA: Randomised clinical trials comparing calcium-channel blockers to placebo or no intervention for people with both tardive dyskinesia and schizophrenia or serious mental illness. DATA COLLECTION AND ANALYSIS: Data were to have been independently extracted and analysed on an intention-to-treat basis. The relative risk (RR) and 95% confidence intervals (CI) of homogeneous dichotomous data were to have been calculated using a random effects model, and, where possible, the number needed to treat calculated. Weighted mean differences (WMD) were to have been calculated for continuous data. MAIN RESULTS: No trials were included. We excluded fourteen studies; eight were not randomised, one did not use calcium channel blockers and five small, randomised, studies reported no usable data. REVIEWER'S CONCLUSIONS: The effects of calcium-channel blockers for antipsychotic induced tardive dyskinesia are unknown. Their use is experimental and should only be given in the context of well designed randomised studies.