Radiosurgical treatment can be carried out by means of a Gamma Knife or a Linear Accelerator. The Linear Accelerator may be either a single-purpose appliance, exclusively employed in radiosurgery, or an adapted appliance, which is used primarily for fractioned radiotherapy, and only additionally for radiosurgical purposes. The first alternative will be referred to briefly as a "dedicated Linac", the latter as an "adapted Linac". Cost accounting data for these alternatives will be discussed under three main categories: investment costs, operating costs, and finally staffing costs. Costs are only considered to the extent that this is necessary to facilitate a comprehensive cost comparison. Factors for which the costs remain the same or at least broadly the same will from the outset not be taken into consideration. These include, for instance, the costs of general or special administration, diagnosis, and image processing. The results and conclusions of this study therefore cannot be employed immediately in the evaluation of cost reimbursement schemes of the type carried out by agencies responsible for social insurance. Here, appropriate complete cost analyses especially for this purpose are required. The final comprehensive cost comparison reveals that the adapted Linac is the most favourable alternative with small annual quantities of patients. With larger numbers of patients the Gamma Knife represents the most favourable from a cost accounting angle. The dedicated Linac accordingly does not have a cost advantage for any of the examined numbers of patients. Clearly the lowest treatment costs per patient can be achieved by employing a Gamma Knife and using it to capacity.