Cutaneous T-cell lymphomas (CTCL) comprise a heterogeneous group of rare diseases that are characterized by a clonal accumulation of T lymphocytes (mainly CD4+) in the skin. The diagnosis is established using an adapted Kiel classification. For staging the present TNM system can be applied, although it is certainly not optimized yet. The choice of treatment modalities depends on the extent and the aggressiveness of CTCL (low- or high-grade lymphoma) and on the individual situation of the patient. A stage-adapted therapy is currently recommended. In stage Ia-IIa we suggest PUVA alone or in combination with retinoids as the first-line therapy. If there is disease progression, interferon-α or methotrexate shall be added. CTCL cases in stage lib can be treated with PUVA combined with interferon-α and soft X-ray radiation (6-8 ×200 cGy, 50 kV twice/week). In stage III (Sézary’s syndrome) photo-pheresis is a well-tolerated first-line therapy which can be supported by interferon-a, methotrexate or retinoids. In case of disease progression, systemic chemotherapy is reasonable (prednisone and chlorambucil or, if resistant, CHOP). Alternatives are radiotherapy (total-skin electron beam) or experimental protocols.