We will describe the method of cost-identification analysis, which was performed in a Dutch hospital during a review of antimicrobial drugs usage. In the present Dutch hospital budget system, in-patients' drug costs generate no revenues. Efforts to diminish drug costs result in financial benefit for the institution. To maximize cost containment, efforts are to be directed to all cost components. We chose wholesale purchase prices of antimicrobial drugs and national prices for salaries and hospital costs. Global cost comparison shows the most cost effective system of intravenous administration. Push injection is the most economic way to administer intravenous drugs which do not require dilution or prolonged infusion time. For stable solutions, such as metronidazole, ready-to-infuse bags are the most economic system. A global cost calculation is listed for commonly used antimicrobial drugs for in-patients. A cost comparison is given for vancomycin CP and teicoplanin, two antistaphyloccocal drugs, which are probably equieffective. The result of global cost comparison contributes to the decision to include new drugs into the hospital formulary or to replace older ones.