The kinetics of fluoride was studied in a group of 3 adult ewes given sodium fluoride solutions at 3 dose levels (0.15, 0.375 and 0.75 mg/kg bw). Data were analysed using both compartmental and noncompartmental approaches. A 3-compartment open model was selected to describe the data. Comparison of the different parameters indicated an absence of change with dose level, suggesting that fluoride behaved linearly at the doses under study. The half-life of elimination was 2.57 +/- 1.28 h, the steady-state volume of distribution was 0.26 +/- 0.5 L/kg and the body clearance was 0.105 +/- 0.26 L/kg/h. It was concluded that a single intravascular fluoride administration (bolus) may be used to evaluate oral bioavailability of fluoride in sheep in toxicity studies.