The pharmacokinetics of temocillin, a new semisynthetic parenteral penicillin, were studied in 10 healthy volunteers. Doses of 0.5, 1.0, and 2.0 g were administered by intravenous bolus injection at weekly intervals, and serum and urine samples were assayed by an agar diffusion method. Mean peak serum concentrations were: 77.9 (+/- 28.4) mg/L (0.5 g), 160.8 (+/- 58.2) mg/L (1.0 g), and 236.1 (+/- 93.3) mg/L (2.0 g), with serum concentrations still being measurable after 12 hours for all doses [7.9 (+/- 3.7) mg/L, 12.9 (+/- 5.2) mg/L, 14.8 (+/- 6.3) mg/L]. According to a 2-compartment open model, the mean terminal half-lives of 0.5, 1.0, and 2.0 g doses were 5.2 (+/- 0.3), 5.0 (+/- 0.2), and 5.0 (+/- 0.2) hours, respectively. The total volume of distribution averaged 0.15 (+/- 0.01), 0.17 (+/- 0.01), and 0.24 (+/- 0.01) L/kg bodyweight, respectively, mean renal clearances were 18.5 (+/- 3.2), 19.6 (+/- 5.0), and 29.8 (+/- 2.6) ml/min, respectively, and the area under the serum concentration time curve (AUC) was 344.1 (+/- 18.7), 573.3 (+/- 27.8), and 784.5 (+/- 47.1) mg X h/L, respectively. At 74 (+/- 12.9)%, the 24-hour urinary recovery was highest for the low dose, followed by 68.1 (+/- 6)% for the 2.0 g dose, and 66.1 (+/- 16.8)% for the 1.0 dose. No untoward side effects were recorded. Thus, temocillin appears to be a penicillin with a prolonged half-life and high AUC.