Abstract： Objective To investigate the in vitro resistance of induced ciprofloxacin- resistant Klebsiella pneumoniae (KPn) to common antibiotics of other categories. Methods Minimum inhibitory concentrations (MIC) of ciprofloxacin in 20 clinically-isolated, sensitive strains of KPn were determined with two-fold agar dilution. Resistance to ciprofloxacin was then developed in these KPn strains by stepwise induction. The K-B diffusion method was used to assess the susceptibility to ceftazidime, cefoxitine,aztreonam, imipenem, moxifloxacin and amikacin among the KPn strains before and after induction.Screening and confirmatory tests for extended spectrum β-lactamases (ESBLs) production were performed after induction. Results Highly ciprofloxacin-resistant strains were successfully induced from 17 of 20 KPn isolates, and ESBL production was found in none of these 17 strains by screening and confirmatory tests. All of the ciprofloxacin- resistant strains were also resistant to moxifloxacin, but sensitive to ceftazidime,imipenem, and aztreonam. Fifteen (88.2％) strains were sensitive to amikacin, 15 (88.2％) resistant and 2(12.8％) intermediate to cefoxitin. Conclusions Long-term low-dose exposure to ciprofloxacin may develop drug-resistance in KPn strains which are cross-resistant to moxifloxacin and cefoxitin. The cross-resistance to cefoxitin in KPn probably shares the similar mechanism that underlies the ciprofloxacin- induced drug resistance.