Oxidative stress is the condition arising from imbalance between toxic reactive oxygen species and antioxidant systems. It is believed that increased oxidative stress may be relevant to the pathophysiology of schizophrenia. In this way, the main markers of the lipid peroxidation processes include 4-hydroxynonenal and malondialdehyde. On the other side, the potential toxicity of free radicals is counteracted by a number of cytoprotective antioxidant enzymes that limit the damage, such as superoxide dismutase and glutathione peroxidase. However, the reports regarding the status of oxidative stress markers schizophrenia are very inconsistent, with various authors stating both increased and decreased activities of the main antioxidant enzymes, while others did not observe any significant modifications, as compared to control groups. Similar aspects were also reported in the case of the lipid peroxidation markers, although in here the contradictions are much more reduced than in the case of the antioxidant defences. It is generally believed that the equivocal results mentioned above may be due to different tissues studies, different species or the administrated treatment and the duration of the disease/treatment. In this context, in the present paper we were interested to review some studies regarding the oxidative stress status in patients and animal models of schizophrenia, by referring mainly to antioxidant enzymes and lipid peroxidation markers.