Erythema multiforme rash on the penis of a 43 year old Hispanic male patient secondary to a herpes simplex virus (HSV) infection. This infection is caused by exposure to HSV-2 (genital herpes) and is usually acquired through a break in the skin. Erythema multiforme is a skin disorder that starts with itchy spots, which then progress to circular weals. Sometimes the bodys internal mucous membranes are affected. The condition can also be caused by some drugs and some cases occur for no obvious reason. Treatment is of the underlying cause. Treatment od HSV infection is with antiviral drugs.