The purpose of this study was to investigate the possible role of reactive oxygen species (ROS) generated by neutrophils in mediating acne inflammation. Antibiotics used for the treatment of acne significantly inhibited ROS generated by neutrophils, when compared to other antibiotics. Metronidazole, which is effective in the treatment of acne, markedly inhibited ROS generated by neutrophils. The drug is known to have no significant effect on the growth of Propionibacterium acnes. The proportion of linoleic acid is markedly decreased in acne comedones. Linoleic acid significantly suppressed ROS generated by neutrophils. The ability of neutrophils to produce ROS was significantly increased in patients with acne inflammation. These results seem to reveal the involvement of ROS generated by neutrophils in the disruption of the integrity of the follicular epithelium, which is responsible for inflammatory processes of acne.