Abstract: AIM: To determine the concentration of terbutaline in human serum and study the pharmacokinetics of terbutaline in Chinese male volunteers following a 7.5 mg oral dose. METHODS: A liquid chromatographicmass spectrometric assay has been developed for the determination of terbutaline in human serum. Mobile phase: 2% glacial acetic acid — isopropanol (98.5∶1.5); chromatographic column: Shimadzu VP-ODS, 5μm, 4.6 mm×150 mm; flow rate: 0.5 mL·min^-1; column temperature: 30℃. RESULTS: Assay linearity was obtained in the range of 0.2～20ng·mL^-1(γ=0.9998). The recovery of terbutaline from human serum was more than 90%. The intra and interassay relative standard deviations for the lowest concentration (0.5ng·mL^-1) examined were 8.2% and 12.9%, respectively. The method was utilized to determine the concentrations of terbutaline in Chinese male volunteers. The concentration — time curve was fitted to a twocompartment model. Its main pharmacokinetic parameters were: T_max=(4.6±1.6) h, C_max=(8.07±1.78) ng·mL^-1, T_1/2β=(9.83±2.21) h. CONCLUSION: The method is sensitive and specific enough to determine accurately the concentration of terbutaline in serum.