The Mycosis Fungoides Cooperative Group has been following patients with cutaneous T-cell lymphoma, including mycosis fungoides and the Sézary syndrome variant. Previous analyses identified the extent of skin involvement and the number of sites of clinically enlarged lymph nodes as important prognostic variables. These two variables were used to classify 340 patients into four clinical stages. Repeat analysis based on additional followup data shows the usefulness of this clinical staging system for identifying patients with differing survival experience. An alternative grouping suggested by fitting a survival model to the data also has been studied. Staging systems based only on skin involvement and lymph nodes are recommended for general use because the information needed is readily available, requiring only physical examination.