Psoriasis is among the most common dermatological diseases worldwide. Its significance is emphasized by adverse effects on quality of life, caused by chronic pain, physical and psychical disability due to psoriatic plaques. Besides the development of psoriatic arthritis, which often causes permanent joint damage, former studies revealed an increased risk of inflammatory bowel disease, cardiovascular disease and certain types of cancer. Genetic predisposition and oxidative stress caused by exogenous and endogenous factors can contribute to abnormal differentiation and hyper-proliferation of keratinocytes, accordingly the development and maintenance of psoriasis. Moreover, excessive oxidative stress can be responsible for the onset of psoriasis complications. After a brief pathophysiological summary the authors discuss the role of oxidative stress in the development of psoriasis and its complications through several well studied biomarkers (asymmetric dimethylarginine, malondialdehyde, superoxide dismutase, catalase).