Peer support workers - people with their own lived experience of mental illness - provide mutually supportive relationships in secondary mental health services. Increasing numbers are being employed, both in this country and elsewhere. This paper is a first attempt at assessing whether peer support provides value for money. Specifically, it looks at whether peer support workers can reduce psychiatric inpatient bed use, either by preventing admissions or by shortening lengths of stay. The authors searched the literature on peer support workers for studies with quantitative data on the relationship between the employment of peers and psychiatric hospital bed use. They used the Cochrane guidelines to assess these studies for risk of bias, and to determine their overall quality. Not all of the studies considered were randomised controlled trials. Eight studies were identified for analysis, of which six studes were identified as using peer support workers to provide "additional" services. This paper concentrates on analysing data in these six studies: five from the US and one from Australia. Notwithstanding limitations in the analysis, it finds that because of the very high cost of inpatient care, the savings that result from even small changes in bed use may be sufficient to outweigh the costs of employing peer workers.