Fluoroquinolones are generally well-tolerated antibiotics in patients. Gastrointestinal, central nervous system, and dermatological adverse events were the most frequent unwanted effects during therapy with these drugs. However, the mechanism of these adverse effects has not yet been elucidated. The aim of this study was to investigate the possible DNA damage-inducing effect of a fluoroquinolone (FQ) antibiotic, ciprofloxacin (CPFX) on primary culture of rat astrocytes. For this purpose, the cultured cells were incubated with various concentrations of CPFX, and DNA damage was monitored by comet assay. Our results showed a concentration-dependent induction of DNA damage by CPFX. Pretreatment of cells with Vitamin E for 4 h provided partial protection against this effect. The data obtained in this study suggest that CPFX-induced DNA damage might be related to oxidative stress and should be considered for further mechanistic studies of central nervous system toxicity of CPFX. (C) 2005 Elsevier Inc. All rights reserved.