The pharmacokinetics and bioequivalence of two norfloxacin, Gentle capsule and Baccidal tablet, were compared in eight healthy male volunteers. A 400 mg dose of norfloxacin was given orally after an overnight fasting to volunteers in a balanced two-way cross-over study. Blood samples were obtained at 0, 0.5, 1.0, 2.0, 4.0, 8.0, 12.0 and 24.0 hours after the dosing. Norfloxacin concentration in serum was assayed by a high pressure liquid chromatographic method using an UV detector. All the data was processed by KMCP computer software and the pharmacokinetic parameters were calculated, based on one-compartment model. The results revealed that the maximal concentration (Cmax) of Gentle and Baccidal was 0.96 +/- 0.089 and 0.99 +/- 0.110; the time to reach maximal concentration (Tmax) was 2.0 +/- 0.0 for both; the elimination constant (Kel) was 0.101 +/- 0.006 and 0.098 +/- 0.005 hr-1; the elimination half life (T1/2, beta) was 6.909 +/- 0.483 and 7.094 +/- 0.350 hr; the absorption constant (Ka) was 2.444 +/- 0.188 and 2.490 +/- 0.096 hr-1; the absorption half life (T1/2, alpha) was 0.278 +/- 0.019 and 0.277 +/- 0.010 hr; the area under curve (from 0 to 12 hours) (AUC0-12) was 7.106 +/- 1.065 and 7.380 +/- 1.044 micrograms.hr/ml; and the area under curve (from 0 hour to infinity) (AUC0-infinity) was 9.183 +/- 1.257 and 9.550 +/- 1.300 micrograms.hr/ml respectively. There were no significant difference found between the two groups after statistical analysis with two-way ANOVA (p greater than 0.05). A series of statistical parameters including d%, delta, and 95% C.I. were calculated by a bioequivalence test computer software of Yamaoka Simi. In order to strengthen the statistical evidence, the power of the test (1 - beta) was also calculated. After evaluating all the parameters, there was no significant difference found between the two groups. Therefore, the high similarity of these two formulations is suggested by the authors.