AIM: To compare the pharmacokinetics and relative bioavailability of the domestic and imported sustained-release tablets of gliclazide in healthy volunteers. METHODS:The study was performed by an four-period crossover design with singledose and multiple-dose administration. The plasmadrug concentrations of twenty male healthy volunteers were determined by liquid chromatography with mass spectrum detector method (LC-MS). RESULTS:The pharmacokinetic parameters after a single oral dose of the domestic and imported gliclazide tablets were (7.2+s 1.5) h and (6.9 +1.4) h for tmax, (13.4 ±1.2) h and (13.7 +1.3) h for t1/2, (2.4 +0.8) mg ·L-1and (2.3 ±0.6) mg· L-1 forcmax, (48 ±14)mg · h · L-1 and (48 +14) mg· h · L-1 forAUC0-60,(51+15) mg· h· L-1 and (50±14) mg· h· L-1for AUC0-∞, (22.4 ± 1.9 ) h and (22.8 ± 1.9 ) h for MRT, respectively. The steady state pharmacokinetic parameters after multiple doses of the domestic and imported gliclazide tablets were (6. 1 ± 1.4) h and (6.5+1.4) h for tmax, (4.6±0.9) mg· L-1 and (4.7±1.1) mg· L-1 for cmax, (0.23 ±0.08) mg ·L-1and (0.26±0.08) mg· L-1 forcmin, (1.6±0.3) mg·L-1 and (1.6±0.3) mg · L-1 for mean value of steady plasma-drug concentration (cav),(94±19) mg· h · L-1 and (95 ±20) mg · h · L-1forAUCss, (282 ±33)% and (283 ±43)% for degree of fluctuation DF ), respectively. The relative bioavailability of the domestic gliclazide tablet to the imported gliclazide tablet following a single and multiple dose were ( 102 ± 9) % and (99 ± 10 ) %, respectively. Main pharmacokinetic parameters between the two formulations in both single and multiples dose studies showed no statistical difference ( P >0.05 ). CONCLUSION: The result of two one side t-test shows that the two formulations are bioequivalent.