Oxygen radicals play a significant role in DNA damage and cancer development. These radicals, produced from oxygen reduction, can damage DNA bases and the deoxyribosyl backbone. Recent studies have identified and quantified various DNA adducts formed by these radicals. Oxygen radicals also damage other cellular components, such as lipids, leading to reactive species that can bind to DNA. Endogenous DNA lesions, like 8-OH-dG, are mutagenic and can lead to mutations, such as GC → TA transversions. These findings suggest that oxygen radicals are important carcinogens. Antioxidants, both enzymatic and non-enzymatic, help counteract the effects of these radicals. However, some antioxidants can also act as pro-oxidants under certain conditions. Clinical studies have shown limited effectiveness of antioxidant supplements in reducing cancer incidence. Instead, reducing oxidative stress sources is recommended. This review highlights the role of oxygen radicals in DNA damage and carcinogenesis, emphasizing the importance of antioxidants in protecting against free radicals. Oxygen radicals are produced through normal cellular metabolism and can cause damage to DNA and proteins, contributing to age-related diseases. The electronic structure of oxygen radicals is complex, with dioxygen existing in different states, including triplet and singlet states. Superoxide radicals are formed by adding one electron to dioxygen, while peroxide dianion is formed by adding another electron. The stability of dioxygen is influenced by its electronic configuration and the thermodynamics of its reduction. Oxygen radicals are produced through electron transfer reactions, often in cellular sites such as mitochondria and the endoplasmic reticulum. Understanding the sources and properties of these radicals is crucial for developing strategies to prevent DNA damage and cancer.Oxygen radicals play a significant role in DNA damage and cancer development. These radicals, produced from oxygen reduction, can damage DNA bases and the deoxyribosyl backbone. Recent studies have identified and quantified various DNA adducts formed by these radicals. Oxygen radicals also damage other cellular components, such as lipids, leading to reactive species that can bind to DNA. Endogenous DNA lesions, like 8-OH-dG, are mutagenic and can lead to mutations, such as GC → TA transversions. These findings suggest that oxygen radicals are important carcinogens. Antioxidants, both enzymatic and non-enzymatic, help counteract the effects of these radicals. However, some antioxidants can also act as pro-oxidants under certain conditions. Clinical studies have shown limited effectiveness of antioxidant supplements in reducing cancer incidence. Instead, reducing oxidative stress sources is recommended. This review highlights the role of oxygen radicals in DNA damage and carcinogenesis, emphasizing the importance of antioxidants in protecting against free radicals. Oxygen radicals are produced through normal cellular metabolism and can cause damage to DNA and proteins, contributing to age-related diseases. The electronic structure of oxygen radicals is complex, with dioxygen existing in different states, including triplet and singlet states. Superoxide radicals are formed by adding one electron to dioxygen, while peroxide dianion is formed by adding another electron. The stability of dioxygen is influenced by its electronic configuration and the thermodynamics of its reduction. Oxygen radicals are produced through electron transfer reactions, often in cellular sites such as mitochondria and the endoplasmic reticulum. Understanding the sources and properties of these radicals is crucial for developing strategies to prevent DNA damage and cancer.