Benperidol is a relatively old antipsychotic drug, marketed since 1966, used in Germany for 30 years, but also available in Belgium, Greece, Italy, the Netherlands and the UK. Benperidol is a butyrophenone antipsychotic, with the highest neuroleptic potency in terms of D2 receptor blockade. Those taking it are, therefore, reputed to be at high risk of extrapyramidal side effects, but benperidol's unusual profile may render it of value to subgroups of people with schizophrenia.To examine the clinical effects and safety of benperidol for those with schizophrenia and schizophrenia-like psychoses.The reviewers searched the Cochrane Schizophrenia Group's register (January 2001) which includes relevant randomised controlled trials from the bibliographic databases Biological Abstracts, CINAHL, The Cochrane Library, EMBASE, MEDLINE, PsycLIT, LILACS, PSYNDEX, Sociological Abstracts and Sociofile. We also searched the references of all included studies and contacted pharmaceutical companies and authors of included studies in order to identify further trials.Randomised controlled trials that compared benperidol with other treatments for people with schizophrenia and/or schizophrenia-like psychoses.Citations and, where possible, abstracts were independently inspected by two reviewers and papers were ordered, re-inspected and quality assessed. We independently extracted data but excluded data if loss to follow up was greater than 50%. For homogeneous dichotomous data, we calculated the relative risk (RR), the 95% confidence interval (CI) and, where appropriate, the number needed to treat/harm (NNT/H), on an intention-to-treat basis.We identified only one unpublished poorly randomised controlled trial (N=40, duration 30 days, comparison perphenazine). Although benperidol was inferior to perphenazine (1 RCT, N=40, global state no better or worse RR 8.0 CI 2.1 to 30, NNH 1.4 CI 1 to 2) poor reporting suggests that an overestimate of effect is likely. It was not possible to report other outcomes.Currently, there are insufficient data from randomised trials to assess the clinical effects of benperidol. This interesting compound merits further research.