A group of 243 patients with mycosis fungoides (MF) received treatment with topical applications of dilute aqueous solutions of mechlorethamine and/or systemic chemotherapy over the past 10 years. The likelihood of a complete and relapse-free remission and survival was found to correlate inversely to the magnitude of disease as denoted by a simple staging system. Although disease-free intervals of greater than 3 years have occurred thus far in 32 (13%) patients, the permanency of these remissions and the curability of disease remain uncertain because of the variability of disease progression characteristic of MF. Comparison of treatment results with those published on a large group of patients treated with total-skin electron-beam radiation therapy indicates that the chemotherapeutic approach to the treatment of MF is equally effective in promoting survival.