The presence of infection in organism induces a lot of Immunological reactions accompanied by creating free Radicals and reactive oxygen species (ROS). These play an important role in elimi- nation of bacteries but also in tissue injury in surrounding. The aim of presented study was to focus on monitoring of ROS and phagocyte activitation in subjects infected by Helicobacter pylori (HP) and thus to contribute to our knowledge of the etiopathogenic role of HP in inflammatory gastrointestinal diseases. The results report some differences, which interpretation opens a lot of questions showing how important of role ROS in HP infection may play.

        Key words: Reactive oxygen species - Phagocyte activation - Helicobacter pylori infection