OBJECTIVE: To review recent studies of systemic therapy for mycosis fungoides and the Sézary syndrome (cutaneous T-cell lymphomas). DATA SOURCES: English-language articles indexed in MEDLINE from 1988 through 1994. STUDY SELECTION: All therapeutic studies were selected. DATA EXTRACTION: The data were abstracted without judgments on response criteria or patient numbers. Data quality and validity were assessed by independent author reviews. DATA SYNTHESIS: No systemic therapy cures patients with cutaneous T-cell lymphomas. Single and combined chemotherapeutic agents produce high response rates. Whether any of these is preferred is not established. A randomized trial comparing combination chemotherapy plus radiation therapy with topical therapy showed no survival benefit for the combination. Several adenosine analogs and retinoids were active, but their optimal use is uncertain. Interferons are as active as chemotherapeutic agents and may be less toxic. Interferon combined with psoralen plus ultraviolet A light therapy produces high complete response rates and long-lasting remissions. Combinations with other systemic therapies do not increase response rates. Photopheresis therapy should be regarded as experimental. Promising preliminary results were seen with interleukin-2 fusion toxins and several antibody conjugates. CONCLUSIONS: Systemic therapy should be considered effective and palliative. The principles of treating all low-grade lymphomas can be applied. Randomized trials are needed to evaluate new agents (such as a comparison of psoralen plus ultraviolet light with or without interferon), and large phase II trials are needed for new agents such as photopheresis, interleukin-2 fusion toxin, temozolomide, and others.