This study was undertaken to evaluate the pharmacokinetics of relatively high-dose vancomycin when administered during high-flux hemodialysis using a polysulfone membrane (F-80, Fresenius). Five noninfected, anuric patients received a single dose of 25 mg/kg of vancomycin infused during hemodialysis at a rate of one gram per hour and timed such that the end of the infusion coincided with the end of dialysis. Blood samples were drawn during the infusion, up to six hours after the end of dialysis and then prior to the next three dialysis treatments. Spent dialysate was collected during the infusion. Samples were analyzed using the EMIT assay. The percent of vancomycin lost during the first dialysis session ranged from 39.1 to 55.1% (mean, 45.7+/-6.4). The concentration of vancomycin at 6 hours after hemodialysis ranged from 18.2 to 45.1 mg/L (mean, 29.6+/-10.0 mg/l). Dialysis clearance ranged from 96.1 to 158.1 ml/min (mean, 130.7 +/-30.0 ml/min). One week after dosing, serum concentrations ranged from 8.14 mg/l to 10.1 mg/l (mean, 9.0+/-1.0 mg/l). This study suggests than an initial dose of 25 mg/kg of vancomycin, given during high-flux dialysis, may provide adequate serum concentrations in anuric hemodialysis patients for up to seven days. This dosing scheme reduces inconvenience to the patient and staff, and potentially can reduce nursing costs associated with post-dialysis administration; its cost is minimal. At this point, subsequent dosing is best determined by therapeutic drug monitoring.