The clinical course of ninety patients with the histopathologic diagnosis of mycosis fungoides is reviewed. An attempt is made to correlate sex, age, of onset, lesion type, and form of therapy with outcome of the disease. The data indicate that mycosis fungoides affects predominantly middle-aged males. Patients developing tumors or erythroderma in middle age or later tend to have a shorter survival. More aggressive therapy is associated with shortened survival. Most deaths were due to unknown or unrelated processes and therapeutic complications. The data support the theory that mycosis fungoides can be a relatively nonaggressive cutaneous lymphoma. In an attempt to treat aggressively, we may be exposing patients to increased mortality.