A clinical trial of clindamycin 900 mg q8h admixed with gentamicin 1.5 mg/kg (eight-hourly group) versus clindamycin 600 mg q6h with gentamicin 1.5 mg/kg given separately (six-hourly group) was analyzed for relative cost containment. Acquisition costs were significantly higher for the six-hourly group for intravenous supplies ($181.5 +/- 47.8) when compared with the eight-hourly group ($67.6 +/- 21.6) (p less than 0.05). Nursing administration costs were greater for the six-hourly group ($28.6 +/- 7.5) compared with ($10.7 +/- 3.4) for the eight-hourly group (p less than 0.05). Also, significantly higher cost (p less than 0.05) was noted for pharmacist and technician manufacturing cost for the six-hourly group ($15.4 +/- 4.0) compared with the eight-hourly group ($13.3 +/- 4.3). Incorporating all appropriate costs, the mean total drug therapy costs were significantly greater (p less than 0.05) for clindamycin 600 mg q6h ($527.4 +/- 143.0) compared with clindamycin 900 mg q8h ($433.3 +/- 99.2). The dosing of clindamycin 900 mg q8h admixed with gentamicin 1.5 mg/kg is a more cost-effective method of drug delivery with similar efficacy and safety when compared with clindamycin 600 mg q6h with gentamicin given separately.