Reactive oxygen species (ROS) play a critical role in inflammatory disorders and tissue injury. They are produced by various cells, including polymorphonuclear neutrophils (PMNs), and contribute to endothelial dysfunction and tissue damage. ROS are generated through multiple pathways, including NADPH oxidase, mitochondrial activity, uncoupled nitric oxide synthase (NOS), and xanthine oxidase (XO). These ROS can lead to oxidative stress, which disrupts endothelial integrity and promotes leukocyte migration across the endothelial barrier. ROS also contribute to the activation of inflammatory signaling pathways, such as those involving calcium, myosin light chain kinase, and toll-like receptors. The review highlights the role of ROS in both acute and chronic inflammation, emphasizing their involvement in cell death pathways and tissue injury. Antioxidant defense systems, including superoxide dismutase (SOD), catalase, and glutathione peroxidase, help mitigate ROS-induced damage. However, excessive ROS production can lead to oxidative stress, which exacerbates inflammation and tissue injury. The review also discusses the importance of ROS in various inflammatory conditions, such as atherosclerosis, diabetes, and autoimmune diseases, and the potential therapeutic implications of targeting ROS pathways. Overall, ROS are central to the inflammatory response and tissue injury, and their regulation is crucial for maintaining homeostasis.Reactive oxygen species (ROS) play a critical role in inflammatory disorders and tissue injury. They are produced by various cells, including polymorphonuclear neutrophils (PMNs), and contribute to endothelial dysfunction and tissue damage. ROS are generated through multiple pathways, including NADPH oxidase, mitochondrial activity, uncoupled nitric oxide synthase (NOS), and xanthine oxidase (XO). These ROS can lead to oxidative stress, which disrupts endothelial integrity and promotes leukocyte migration across the endothelial barrier. ROS also contribute to the activation of inflammatory signaling pathways, such as those involving calcium, myosin light chain kinase, and toll-like receptors. The review highlights the role of ROS in both acute and chronic inflammation, emphasizing their involvement in cell death pathways and tissue injury. Antioxidant defense systems, including superoxide dismutase (SOD), catalase, and glutathione peroxidase, help mitigate ROS-induced damage. However, excessive ROS production can lead to oxidative stress, which exacerbates inflammation and tissue injury. The review also discusses the importance of ROS in various inflammatory conditions, such as atherosclerosis, diabetes, and autoimmune diseases, and the potential therapeutic implications of targeting ROS pathways. Overall, ROS are central to the inflammatory response and tissue injury, and their regulation is crucial for maintaining homeostasis.