Abstract ? Twenty-six Swedish dental health care clinics participating in the intervention study ?Evaluation of caries preventive measures? have been analysed with focus on costs, with the aim of demonstrating techniques suitable for evaluating direct dental care costs and also finding out whether charges are acceptable as a proxy for real costs. Three different approaches to calculating unit costs are discussed: average treatment time cost and two methods of different allocation of overhead cost. Average treatment time cost shows treatment time cost regardless of who (dentist, dental hygienist or nurse) provides the dental care. The other two methods reflect both the differences of treatment costs depending on practitioners' skill level and competence (salary) an the methods of handling overhead cost allocation. Our conclusions are that the proposed methods seem useful for evaluating costs in cost-effectiveness and cost-benet analysis. The alternative to average treatment time cost or unit time cost depends on what data is available and the perspective of the analysis. This study also concludes that charges are not sufficient as an alternative to a more detailed cost evaluation, at least not in Swedish public dental health care, since charges do not cover costs.