The occurrence of both lupus erythematosus and multiple sclerosis in several members within the same family has been previously documented. In the past, patients manifesting symptoms and findings compatible with both of these diseases have posed difficult diagnostic problems. This report concerns a patient with long-standing multiple sclerosis and in whom cutaneous and serologic lupus erythematosus developed. To our knowledge this is the first such case reported in the English literature. A daughter of this patient had developed serologic lupus erythematosus. The intensified study of patients with both of these diseases and those families with several members with one of these diseases may lead to new insights into the cause and pathogenesis of these disorders.