In some instances histologic examination of lesions of the skin of various types for diagnostic purposes is conclusive; in other cases such examination has little, if any, merit, and in still other cases such examination may not be specific, but may possess considerable value. Lupus erythematosus belongs to the last group. Considerable diagnostic evidence can be obtained by proper evaluation of a combination of histologic changes which, taken separately, are not significant. A summary of such an estimate is attempted in this study, based on twenty-six cases of the discoid type and eighteen cases of the disseminate type. The results obtained are emphasized regarding: (1) changes as accepted in the modern literature; (2) changes concerning which the authors are not agreed; (3) comparison of changes in the discoid and disseminate types, and (4) value of the changes in differential diagnosis. CHANGES AS ACCEPTED IN THE MODERN LITERATURE A