Ultra violet radiation (UVR) is an important feature for the development or aggravation of several dermatologic diseases. In autoimmune skin diseases it has been suggested as an important cofactor in autoimmune bullous skin diseases and more importantly cutaneous lupus erythematosus (CLE). The pathophysiological role of UVR in CLE is a result of several effects which are triggered by UVR. In detail UVR induces apoptosis of keratinocytes and an abnormal local immune response which triggers inflammation in the skin. These findings result in the clinical approach of a stringent UVR protection in affected patients. Currently UVR protection is advised to patients as a supportive measure but cannot be prescribed to patients as these products are not licensed. Well-defined prospective placebo controlled studies regarding UVR protection are missing.