The drugs described in this thesis are extremely potent and produce many adverse reactions. Because side effects often make these drugs unsuitable for most benign dermatologic conditions, they are used mainly for malignancies or for immunosuppression. However, they can be extremely valuable, with proper monitoring, in the treatment of certain severe skin disease. Individualized risk analysis for cytotoxic drug use in dermatology must be undertaken for each individual patient with skin disease. The clinician should appreciate the generally lower inherent disease risk to these patients than to patients with internal malignancies or in organ transplantation. The major uses of cytotoxic drugs have been for life threatening cutaneous and systemic disorders or as steroid sparing agents. Disorders suh as permphigus vulgaris and dermatomyositis may result in death if not adequately treated. Although corticosteroids are often effective, immunosuppressive cytotoxic agents may be used when steroid related side effects develop. In other instances, the immunosuppressive agents are the drugs of choice. The cytotoxic agents most useful for dermatologic conditions are covered here. Azathioprine, cyclophosphamid and Methotrexate are covered in detail as well as other drugs.