Background: Glioblastoma multiforme, the most common, aggressive malignant brain tumor which affects patients of all ages, is principally resistant to treatment. Ciprofloxacin is an antibiotic that belongs to the fluoroquinolones. There are welldocumented observations which indicate that ciprofloxacin has substantial anti-proliferative, apoptotic, cytotoxic and oxidative stress activities on various tumor cell lines.Methods: We exposed the glioblastoma A-172 cell line to ciprofloxacin for 24, 48 and 72 h. Cytotoxicity was measured using MTT assay. The levels of Bax as an apoptotic and Bcl-2 as an anti-apoptotic protein were measured by ELISA and oxidative stress by the malondialdehyde assay.Results: Ciprofloxacin induced tumor cell death in a dose-dependent manner with an IC50 value of 259.3 μM at 72 h. We observed an increase in Bax levels, a decrease in Bcl-2 concentrations and increased Bax/Bcl-2 ratio under the influence of ciprofloxacin. Malondialdehyde levels, as an important marker of oxidative stress, increased in the human glioblastoma A-172 cell line.Conclusion: These results indicated that ciprofloxacin had anti-tumor, cytotoxic and apoptotic effects in the human glioblastoma A-172 cell line which might be useful as an adjuvant added to a glioblastoma multiforme chemotherapeutic protocol in the future.