The incidence of non-melanoma skin cancer (NMSC) is increasing. Squamous cell carcinoma of the skin (SCC) is a tumor of the elderly. Due to the increasing life expectancy, SCC will become more and more frequent in the future. Generally SCC has a favorable prognosis. Standard therapy is microscopically- controlled excision. Therapy of advanced and metastatic SCC is still challenging. Patients with regional lymph node metastasis have ten-year survival rates less than 20%; patients with distant metastases less than 10%. Immunosuppression has been shown to be one of the key prognostic factors for metastasis. The article reviews SCC and focusses on patients being at risk for an unfavorable course.