Prompts to encourage attendance at clinics are often used in day-to-day practice by diligent carers of people with mental health problems. These may take the form of telephone prompting, financial incentives or issuing a copy of the referral letter to the appointee. To estimate the effects of simple prompting by professional carers to encourage attendance at clinics for those with serious mental illness. Methodical searches of Biological Abstracts (1985-2000), CINAHL (1982-2000), Cochrane Schizophrenia Group's Register (June 2000), Cochrane Library (Issue 2, 2000), EMBASE (1980-2000), MEDLINE (1966-2000) and PsycLIT (1887-2000) were undertaken. These were supplemented by searching of reference lists, personal contact and hand searching of high yield journals. All relevant randomised (or quasi-randomised) studies comparing the addition of 'prompts' to standard care for those with serious mental illnesses such as schizophrenia. Prompts had the stated purpose of encouraging attendance or contact with mental health teams and could be text-based, electronic, by telephone call, by personal visit, or could employ financial or other rewards. Studies and data were independently selected and extracted. For homogeneous dichotomous data the random effects relative risk (RR), the 95% confidence intervals (CI) and, where appropriate, the number needed to treat (NNT) were calculated on an intention-to-treat basis. For continuous data the reviewers calculated weighted mean differences. Only three relevant trials were identified (total n=597). It is not clear whether there is any real difference between attendance of those prompted by telephone one or two days before the appointment, and those given the standard appointment management system (2 trials, n=457, RR missed appointment 0.84 CI 0.7 to 1.1). Text-based prompts, a few days before the appointment day, did increase clinic attendance when compared with no prompt (2 trials, n=200, RR missed appointment 0.6 CI 0.4 to 0.9, NNT 6 CI 2 to 14). Only one small study (n=61) reported data on the combination of telephone and text-based prompts versus no prompt (RR missed appointments 0.7 CI 0.4 to 1.2). When telephone prompts were compared with text-based prompts (1 trial, n=75), the latter, in the form of an 'orientation statement' (a short paragraph, taking about 30 seconds to read, explaining the programme of care, the fee system, and providing gentle encouragement) may be somewhat more effective than the telephone prompt (RR missed appointments 1.9 CI 0.98 to 3.8). One last study (n=120) compared a standard letter prompt with a letter 'orientation statement'. Overall, results tended to favour the orientation statement approach rather than the simple letter prompting attendance but the results did not reach conventional levels of statistical significance (RR missed appointments 1.6 CI 0.9 to 2.9). There is evidence that a simple prompt to attend clinic, very close to the time of the appointment may encourage attendance, and a simple orientation-type letter, 24 hours before the clinic appointment, may be more effective than a telephone prompt. This simple intervention could be a more cost effective means of encouraging compliance at first attendance, but supplementing these data with the results of large, well designed, conducted and reported randomised studies would be desirable.