Glycosaminoglycans (GAGs), components of extracellular matrix, are thought to play important roles in cell proliferation and differentiation in the repair process of injured tissue. Oxidative stress is one of the most frequent causes of tissue and cell injury and the consequent lipid peroxidation is the main manifestation of free radical damage. It has been found to play an important role in the evolution of cell death. Since several reports have shown that hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S) are able to inhibit lipid peroxidation during oxidative stress, We investigated the antioxidant capacity of these GAGs in reducing oxidative damage in fibroblast cultures. Free radicals production was induced by the oxidizing system employing iron (Fe2+) plus ascorbate. We evaluated cell death, membrane lipid peroxidation, DNA damage, protein oxidation, hydroxyl radical (OH*) generation and endogenous antioxidant depletion in human skin fibroblast cultures. The exposition of fibroblasts to FeSO4 and ascorbate caused inhibition of cell growth and cell death, increased OH* production determined by the aromatic trap method; furthermore it caused DNA strand breaks and protein oxidation as shown by the DNA fragments analysis and protein carbonyl content, respectively. Moreover, it enhanced lipid peroxidation evaluated by the analysis of conjugated dienes (CD) and decreased antioxidant defenses assayed by means of measurement of superoxide dismutase (SOD) and catalase (CAT) activities. When fibroblasts were treated with two different doses of HYA or C4S a protective effect, following oxidative stress induction, was shown. In fact these GAGs were able to limit cell death, reduced DNA fragmentation and protein oxidation, decreased OH* generation, inhibited lipid peroxidation and improved antioxidant defenses. Our results confirm the antioxidant activity of HYA and C4S and this could represent a useful step in the understanding of the exact role played by GAGs in living organisms.