This study was carried out to evaluate the safety, timing and cost-effectiveness of administering perioperative antimicrobial prophylaxis with cefmetazole via intravenous (IV) bolus, or 'push', compared with the more common method of IV 'piggyback' administration. A total of 60 patients were studied, 30 in each group. No major adverse reactions were noted in either group. Phlebitis did not occur with either method of administration. Loss of patency was noted in 2 patients in the IV bolus group at the time of catheter removal. While no overall difference in timing of antibiotic administration in relation to the surgical procedure was noted, 2 patients in the IV piggyback group did not receive their preoperative dose until after surgery had started. Both pharmacy preparation time and nursing administration time were shorter with the IV push method, resulting in a cost avoidance of $US0.60 per dose. Material cost avoidance, primarily due to elimination of the minibag and IV tubing with bolus administration, was $US3.25 per dose. Extrapolated cost avoidance for our institution, for both prophylaxis and treatment, is $US184 000 per year. Administration of selected antibiotics by IV push is safe, allows optimal timing of administration, minimises preparation and administration time, and is cost-effective. Hospitals and outpatient care facilities should consider this alternative method of antibiotic administration.