Peer support groups are rarely available for patients with psychosis, despite potential clinical and economic advantages of such groups. In this study, 106 patients with psychosis were randomly allocated to minimally guided peer support in addition to care as usual (CAU), or CAU only. No relevant differences between mean total costs of both groups were found, nor were there significant differences in WHOQoL-Bref outcomes. Intervention adherence had a substantial impact on the results. It was concluded that minimally guided peer support groups for psychosis do not seem to affect overall healthcare expenses. Positive results of additional outcomes, including a significant increase in social contacts and esteem support, favour the wider implementation of such groups. © 2009 Springer Science+Business Media, LLC.