Community psychiatric nurses (CPNs) in the United Kingdom are increasingly working in primary health care settings with less serious mental health problems. This paper describes an economic evaluation of their work using a randomized controlled trial in which 231 patients were assigned to continuing general practitioner care or one of two conditions of CPN intervention. This is only the third systematic economic analysis of community mental health nursing in the UK and the first carried out by mental health nurses. Various costs to patients, their families and the health care system were determined. Results showed that patients receiving CPN intervention experienced less absence from work and that this resulted in a net benefit. However, the cost per quality adjusted life year for intervening with this group of patients was probably several times more than for intervening with the seriously mentally ill. Therefore, if one considers both the clinical and economic results of the study, taken together with the recent results of the review of mental health nursing, there seems little justification for CPNs continuing to work in this area.