Herpes simplex virus (HSV) 1 commonly causes local skin infection around the mouth and face. However, infection may become widespread and can be more severe especially in people with immunodeficiency. Methotrexate is an antiproliferative and antifolate drug which is used successfully in the treatment of chronic inflammatory diseases such as rheumatoid arthritis. On the other hand, it is associated with severe toxicity and side effects. In this article, a 53-year-old patient who applied to our hospital due to the rashes all over the body and apparent around the mouth, beside fever is presented. The patient who has been receiving methotrexate treatment because of rheumatoid arthritis had kidney transplantation five years ago. HSV 1 viremia was detected in the patient and the symptoms improved quickly with acyclovir. Klimik Dergisi 2016; 29(1): 43-6.