Cutaneous T-cell lymphoma (CTCL) is typically a skin-infiltrating malignancy of clonally derived CD4+ T lymphocytes. Because the host antitumor response appears to play an important role in disease control, systemic therapeutic agents are used in such a manner as to preserve the integrity of the host antitumor response while selectively targeting the malignant cells. The new biologic response-modifying treatment options currently used to treat CTCL are reviewed.