Background: Acinetobacter baumannii isolates resistant to fluoroquinolones, such as levofloxacin and ciprofloxacin are being increasingly developed every day. Objectives: In this study, ciprofloxacin resistance in A. baumannii isolates was determined by the presence or absence of efflux pump inhibitors, as the efflux pumps play an important role in the creation of ciprofloxacin resistance. Methods: One hundred and three Acinetobacter isolates were collected from ventilator-associated pneumonia (VAP) and burn patients of Tehran hospitals, Iran, during six months of 2014. Susceptibility rates of the isolates to levofloxacin and ciprofloxacin antibiotics were assessed using the agar disk diffusion and broth microdilution. The effects of the efflux pump inhibitors including