OBJECTIVES: During last decade Slovakia has been undergoing a transformation of its economy and the health care has also been completely changed. A system of health insurance had to be created and regulation tools to restrain growing expenditures, especially drug costs, had to be introduced. Nowadays one of the most developed tools is reimbursement scheme based on ATC (anatomic, therapeutic and chemical classification of WHO) & DDD (defined-daily dose) classification. The substance of this system and financial impact of reimbursement reviews are to be presented herein. METHODS: Mathematical modeling of current costs and expected costs were applied. Impact of non-quantitative reimbursement changes aimed at rationalizing of prescription were also analyzed. All calculations were made on the basis of health insurance data regarding drug consumption compulsorily reported to the Ministry of Health. RESULTS: Due to reimbursement review, difference between the drug costs trends (assuming constant reimbursement levels) and actual costs (reimbursement changes are included) for the period of 1996 through 2002 stands for approximately SKK 3.9 billion. This figure represents the savings of health insurance funds, which can be used for other purposes. CONCLUSIONS: Drug costs monitoring system, through obligatory reports of health insurance companies to the Ministry of Health, together with reimbursement level set per one DDD of drug enable us to influence drug costs through reimbursement reviews. Nowadays some steps to equalize the reimbursement levels of different active substances are being taken and large database analysis are in progress. It should also be emphasized that all countries are confronted with health costs increase regardless of their level of economic development. They are creating their own system of dealing with drug containment. In order to facilitate the development of most effective regulation tools the information exchange should start.