In this double-blind, randomized study, five healthy subjects per group received doses of 15, 20, or 25 mg of teicoplanin per kg of body weight, and one subject per group received a 0.9% NaCl placebo as single intravenous infusion over 30 min. Serial blood samples and urine were collected for 13 days postadministration, and concentrations of teicoplanin were determined by microbiological assay. The pharmacokinetic data were analyzed by noncompartmental and compartmental analyses. Laboratory safety tests, audiometry, and serum creatinine clearance measurements were done prior to day 1 and on days 2 and 14. In the three groups, peak levels at the end of the infusion averaged 194, 197, and 253 mg/liter, respectively. Mean concentrations in plasma 24 h after the administration were 10.5, 13.6, and 19.8 mg/liter, respectively. Mean values of volume of distribution at steady state were 0.80, 0.87, and 0.87 liters/kg, respectively. Terminal half-lives averaged 88, 83, and 92 h. Mean total clearance values were 10.9, 11.0, and 11.3 mg/h/kg, respectively, with renal clearance accounting for 75, 81, and 78%, respectively, of the total. The 13-day cumulative mean urinary recovery ranged from 71 to 78% of the dose within the groups. The pharmacokinetics of teicoplanin appears to be linear in the range of administered doses. Teicoplanin was generally well tolerated. Side effects, appearing in five subjects, were represented by fevers, chills, and skin reactions; these adverse reactions were mild, but one episode of rash necessitated the interruption of infusion, and one episode of chills necessitated treatment with corticosteroids. There was no indication of drug-related modifications of laboratory test results.