Darlenski R, et al. - Authors herein aimed to address the link between disease activity, epidermal barrier and systemic oxidative stress in the course of 311 nm narrowband ultraviolet B (NB-UVB) therapy of psoriasis. Beneficial effects of a clinical improvement of psoriatic plaques under NB-UVB therapy, shown in with a decreased psoriasis area and severity index (PASI) and reflected by an increase in quality of life had beneficial effects on epidermal barrier function, stratum corneum hydration (SCH), and improvement of systemic oxidative stress parameters [reactive oxygen species (ROS), malondialdehyde (MDA), and ascorbyl radicals (Asc)]. Researchers assumed that the improvement of disease activity was mainly reflected in the general improvement in the oxidative stress parameters along with epidermal barrier parameters which overwrote the possible negative pro-oxidative effects of the UV treatment.