Subinhibitory concentrations of antibiotics have been shown to alter the virulence of microorganisms, which may modify the progression of infection. This study assessed the induction of nitric oxide and apoptosis on macrophages infected by Helicobacter pylori exposed to subinhibitory concentrations of amoxicillin. RAW 264.7 (macrophagelike cells) infected with H. pylori amoxicilin-treated significantly increased the levels of nitric oxide and apoptosis ininfected macrophages as compared to H. pylori without treatment. These results suggest that amoxicillin at subinhibitory concentrations can contribute