Abstract. Despite recent advances in preterm newborns healthcare, the incidence of neonatal pathologies and disabilities still remain unacceptable high. The deficiency of antioxidant systems and the high free radicals (FRs) production may cause several neonatal diseases, such as Retinopathy of Prematurity (ROP), Bronchopulmonary Dysplasia (BPD), Necrotizing Enterocolitis (NEC), Patent Ductus Arteriosus (PDA), Periventricular Leukomalacia (PVL) and Intraventricular Hemorrhage (IVH), representing facets of the 'Free Radical-Related Diseases' (FRD). The aim of this study is to verify the association between FRD and blood levels of reliable oxidative stress (OS) biomarkers in preterm newborns. We enrolled 178 preterm newborns born consecutively at the General Hospital "Santa Maria alle Scotte" in Siena, between 23 and 34 weeks (30,36±2.97) of gestational age, with birth-weight from 430 to 2890 grams (1453±593). After birth, we evaluated in the cord blood the markers of potential risk of OS (Non Protein-Bound Iron, NPBI) and the markers of FR damage (Total Hydroperoxides, TH; Advanced Oxidation Protein Products, AOPP). For each newborn, we assessed the presence or absence of the following diseases, considering as FRD the presence of one at least: ROP, BPD, NEC, PDA, PVL, IVH. The univariate logistic regression showed a significant association between FRD and OS related markers. Risk assessment of FRD was higher in newborns with higher values of each OS marker: respectively TH (OR=1.013, p=0,000), AOPP (OR=1.017, p=0,036), NPBI (OR=1.077, p=0.039). Perinatal OS exposure is linked to the main diseases of prematurity. The evaluation of OS biomarkers in preterm newborns through the analysis of umbilical cord blood, can be useful and predictive for early identification of infants at risk for FRD in order to devise appropriate and timely prevention and treating strategies.