Public sector organisations often make use of management consultants in policy implementation, but we know little about the outcomes. The paper reports one of the first quantitative evaluations of the impact of consulting advice on efficiency of public sector organisations. We employ an extensive dataset covering English NHS acute care hospital trusts over a four-year period. Based on PCSEs estimations, the findings show a significantly positive relationship between consulting expenditure and organisational inefficiency. These results lend support to critical accounts of management consulting, highlighting the need for organisations to be circumspect in deciding whether and how to use these services.