A classification of malignant lymphomas has been formulated to identify distinct clinical groups of patients for future therapeutic trials. The unifying concept of primary cutaneous lymphomas as of either T- or B-cell origin does not conflict with the Working Formulation but encompasses its categories. This classification requires immunologic data in addition to morphologic assessment for accurate evaluation. Cytomorphologic subdivision of the cutaneous T-cell lymphomas does not have the same clinical significance as for the cutaneous B-cell lymphomas. However, the pattern of skin involvement in cutaneous T-cell lymphoma (epidermotropic versus nonepidermotropic) does appear to be important clinically and should be included in future classifications.