The aim of this article is to provide politicians with alternative ways of reducing health care expenditures through injury prevention. One way to do this is to present examples of how rationalisation gains resulting from injury prevention can be calculated and how this can be used to influence the direction of health policy. The calculations in the example are based on an estimated incidence of 113 patients per 1,000 population for outpatients and the number of hospitalised patients reported in the patient statistics. The costs of medical and surgical treatment and care have been calculated with the aid of Karolinska Hospital's contract for care of patients from other counties. Based on experience from the Falköping project, the preventive effect has been estimated to be 28 per cent. The approach has also been reviewed according to eight key features of health policy analysis in order to demonstrate new ways of increasing communication. The calculations show that under ideal conditions 316 hospital beds in Stockholm county can be released for other purposes. A dialogue has been started with politicians and administrators for continued discussions in the respective counties. Experience shows that data for calculation of rationalisation gains can be obtained rapidly. For more detailed health economic analyses, a comprehensive injury surveillance system and more detailed patient statistics are necessary.