Oxidative stress is involved in chronic and acute pathologies: cardiovascular, neurodegenerative, neoplastic, inflammatory and infectious diseases. Clinical trials focused on prevention of cardiovascular and neoplastic diseases involving antioxidant supplementation have however provided predominantly negative obserations in large-scale studies. Screening of patient cohorts to assess baseline oxidative stress on the basis of a biomarker profile is decisive but lacking. For the first time, we evaluated the level of oxidative stress, testing more than 10 established biomarkers, in a comprehensive initial survey of 617 patients displaying chronic human pathologies. Multiple diseasespecific abnormalities were identified in plasma, whole blood and/or urine. This is the case for vitamins and oligo elements, vitamin C, vitamin E, β-carotene, selenium, zinc and copper; endogenous antioxidants such as reduced and oxidised glutathione, thiols, urate, and glutathione peroxidase activity, and a biomarker of oxidative DNA damage (8-hydroxy-2’-deoxy guanosine). The distinct biomarker profiles suggest the involvment of multiple forms of oxidative insults which arein some way partially specific to each pathological condition. This finding is in favor of the determination of an integrated score to combine contributions of distinct biomarkers, in order to screen patients presenting elevated levels of oxidative stress.