BACKGROUND AND AIM: 15-F2t-Isoprostane is a product of arachidonic acid non-enzymatic oxidation by free radicals. Validated in animal and clinical models, it is a golden standard tool for the oxidative status assessment. The aim of this study is to assess how this biomarker levels could vary during the lifespan. METHODS: The 15-F2t-Isoprostane urinary concentration was measured in 889 subjects aged between 7 and 69. The analyses were performed by ELISA kit. The levels of 15-F2t-Isoprostane were normalised by creatinine (Kinetic Jaffé method). The analysis was performed considering 10-year age classes: 10 years, 10-19 years, 20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years. RESULTS:The average 15-F2t-Isoprostane levels were 4.41 ± 4.69 ng/mg creatinine. The descriptive analysis reveals an apparent reduction in the age-class 11-19 years (2.78 ± 2.54 ng/mg creatinine). The average predicted values for the age classes resulting from a GLM analysis are: 10 years: 3.72 ng/mg creatinine (p0.001, 95%C.I. 2.87-4.58); 10-19 years: 2.78 ng/mg creatinine (p0.001, 95%C.I. 2.25-3.31); 20-29 years: 4.08 ng/mg creatinine (p0.001, 95%C.I. 3.04-5.12); 30-39 years 5.09 ng/mg creatinine (p0.001, 95%C.I. 4.20-5.98); 40-49 years 4.98 ng/mg creatinine (p0.001, 95%C.I. 4.35-5.60); 50-59 years: 4.28 ng/mg creatinine (p0.001, 95%C.I. 3.68-4.88) and 60-69 years: 5.23 ng/mg creatinine (p0.001, 95%C.I. 3.83-6.62). CONCLUSIONS:Oxidative stress biomarkers levels are currently studied in various populations due to their increase in pre-clinical stages of diseases that could be related to lifestyle, environmental or occupational exposures. The main evidence consists in the reduction in the concentration of 15-F2t-isoprostane in adolescence, which leads to an interruption of the constant increase in oxidative stress over the years. The knowledge of how the 15-F2t-Isoprostane levels change during the lifespan and the assessment of the trend-shape of this phenomenon are crucial to better understand the meaning of this biomarker in molecular epidemiology research. KEYWORDS: Long-term exposure, Environmental epidemiology, Molecular epidemiology