OBJECTIVE: To investigate the effects of tinidazole on the pharmacokinetinetics of levofloxacin (LVFX) in plasma and uterine tissue of pelvic inflammatory model rats. METHODS: Female rats were selected to establish chronic pelvic inflammation model. Those model rats were randomly divided into experimental group (tinidazole 100 mg/kg+lactic acid LVFX suspension 80 mg/kg) and control group (lactic acid LVFX suspension 80 mg/kg), with 48 rats in each group. They were given relevant medicine intragastrically 4th day after modeling. 6 rats were respectively sacrificed 0.25, 0.5, 1, 1.5, 2, 4, 8 and 12 h after medication. The plasma and uterine samples were collected. Using ciprofloxacin as internal standard, the concentrations of LVFX in plasma and uterine tissue were detected by HPLC, and the pharmacokinetic parameters were calculated with DAS 2.0 software. RESULTS: Plasma concentration-time curves of LVFX in plasma and uterine tissue of rats in experimental group and control group both fit the two-compartment model. The main pharmacokinetics parameters as follows as cmax were (15.17±0.87) vs. (14.94±0.46) μg/ml for plasma,(14.18±1.20) vs. (11.86±0.84) μg/ml for uterine tissue; tmax were (1.42±0.20) vs. (1.5±0.01) h for plasma, (1.25±0.27) vs. (1.17±0.26) h for uterine tissue; t1/2β were (7.69±2.61) vs. (7.32±2.80) h for plasma, (7.95±5.29) vs. (9.16±3.00) h for uterine tissue; AUC0-12 h were (52.65±6.07) vs. (51.15±3.53) μg·h/ml for plasma, (52.92±5.87) vs. (42.59±3.91) μg·h/ml for uterine tissue; AUC0-∞ were(61.27±7.93) vs.(58.86±4.58) μg·h/ml for plasma,(60.64±7.20) vs. (47.41±4.75) μg·h/ml for uterine tissue; CL/F were (1.37±0.26) vs. (1.35±0.10) L/(kg·h) for plasma, (1.32±0.16) vs.(1.67±0.17) L/(kg·h) for uterine tissue. There were statistical significance in cmax, AUC0-12 h, AUC0-∞ and CL/F of uterine tissue between 2 groups (P<0.05). CONCLUSIONS: Tinidazole can obviously increase the distribution of LVFX in the uterine tissue of pelvic inflammatory model rats, reduce the elimination rate but has no effect on the distribution of LVFX in plasma.