The cost difference of administering cimetidine 300 mg via intravenous piggyback (IVPB) every six hours by a conventional separate container system versus using an automated intermittent i.v. administration system was evaluated. The study was conducted in two phases. Phase 1 documented the amount of drug waste with the two systems, and phase 2 examined the practical use of the IVAC Multi Dose System. Nurses who administered the medication using the multiple-dose system completed a questionnaire on its operation. A materials cost analysis was performed to compare the two methods. The two systems were found to have approximately equivalent amounts of drug waste over the 30-day evaluation period of phase 1. The mean percentage of doses wasted was 12.2% with the conventional single-dose minibag method and 12.7% with the automated multiple-dose method. The multiple-dose system had a lower cost per dose of cimetidine ($2.25 versus $3.47). These savings appear to outweigh the cost of the additional equipment necessary for the automated system. The majority of nurses preferred the multiple-dose system. Potential problems encountered in accurately delivering doses with the multiple-dose automated system were identified, and possible solutions are suggested. The use of an automated multiple-dose i.v. administration system can potentially decrease the materials cost portion of drug administration. The total impact on hospital costs needs to be evaluated, and other comparisons with alternative administration systems need to be performed.