Abstract: Rabbits in pairs ware randonly divided into two groups, a group given rifandin and a control group. After a single iv injection of dexamethasone sodium phosphate, the concentrations of dexaethasone in rabbit plasma at a series of time were analysed by HPLC on ODS (5μ) column (125×4.5 mm) with CH₃OH—H₂O (70:30) as mobile phase (0.6ml/min) and detected at 254 nm. Linear regression analysis was made by LnC(t)-t, the results indicate that the data fitted a twocompartment open model adequately. The pharmacokinetic parameters of dexame thasone in rabbits were calculated by methods of residuals. T test in pairs between groups of primary parameters, K₁₀, t 1/2β and AUD^0～∞/kg showed that rifandin apparently promote metabolic clearance of dexamethasone in plasma.