Healthcare professionals working in the community do not always prescribe oral nutritional supplements (ONS) according to best practice guidelines for the management of malnutrition. The present study aimed to determine the impact of a community dietetics intervention on ONS prescribing practices and expenditure 1 year later.The intervention involved general practitioners (GPs), practice nurses, nurses in local nursing homes and community nurses. It comprised an education programme together with the provision of a new community dietetics service. Changes in health care professionals' nutrition care practices were determined by examining community dietetics records. ONS prescribing volume and expenditure on ONS were assessed using data from the Primary Care Reimbursement Service of the Irish Health Service Executive.Seven out of 10 principal GPs participated in the nutrition education programme. One year later, screening for malnutrition risk was better, dietary advice was provided more often, referral to the community dietetics service improved and ONS were prescribed for a greater proportion of patients at 'high risk' of malnutrition than before (88% versus 37%; P0.001). There was a trend towards fewer patients being prescribed ONS (18% reduction; P = 0.074) and there was no significant change in expenditure on ONS by participating GPs (3% reduction; P = 0.499), despite a 28% increase nationally by GPs on ONS.The community dietetics intervention improved ONS prescribing practices by GPs and nurses, in accordance with best practice guidelines, without increasing expenditure on ONS during the year after intervention.