Objective To compare the systematic and lung pharmacokinetic parameters of moxifloxacin hydrochloride and explore a feasible tool to monitor drug concentration and evaluate therapeutic efficacy of respiratory fluoroquinolones. Methods Ten adult patients with community-acquired pneumonia or acute exacerbation of chronic bronchitis were enrolled.The subjects received a single dose of oral moxifloxacin hydrochloride 400 mg. Serum specimens were sampled at 0，1，2，3，4，8，24 h and sputum specimens were collected 0，1，2，4，8，20，24 h after administration，respectively.The serum and sputum concentrations of moxifloxacin hydrochloride were assayed by means of high-performance liquid chromatography. Standard pharmacokinetic parameters including peak concentrations(Cmax) and area under the concentration-time curve (AUC0-24 h) were assessed. Results Serum C(max) was（5.95±1.35）mg/L at 2 hours and serum AUC0-24 h was (58.72±8.11）mg·h-1·L-1 while sputum Cmax and AUC0-24 h were （16.18±6.47）mg/L at 3 hours and （138.04±78.29）mg·h-1·L-1 respectively，which were significantly higher than those in serum. Conclusion Oral administration of moxifloxacin hydrochloride to patients with respiratory infections results in rapid penetration into lung and maintain a one-fold drug concentration compared to blood concentration within 24 hours.Sputum drug concentration analysis demonstrates a superior pharmacokinetic profile of moxifloxacin in respiratory tract.