Background: Despite randomized controlled trials (RCTs) being regarded as the gold standard for intervention research in mental health, there is a lack of guidance on the practicalities of setting up and conducting such trials in the NHS. Aims: To provide information for new clinical trials collated from the experiences of carrying out the NCCHTA-funded CUtLASS trial (reported in an HTA Monograph entitled "Randomised controlled trials of conventional versus new atypical drugs, and new atypical drugs versus clozapine, in people with schizophrenia responding poorly to, or intolerant of, current drug treatment"). Conclusions: The main practical considerations in clinical trials can be grouped into issues of Staffing, Trial Management and Data Management. Matters that impact on recruitment include the research question, the interest of clinicians in that question, the extent of clinical equipoise, and the provision of adequate reimbursement of service support costs associated with participation in the trial. © Shadowfax Publishing and Taylor & Francis Group Ltd.