The case of a 40-year-old woman with Werner's syndrome associated with systemic lupus erythematosus (SLE) is reported. The patient exhibited short stature, slender extremities, thinned hair, high-pitched voice, cataracts, ulceration of the fingers, and mental retardation. Malar erythema, photosensitivity, and proteinuria had been noted since age 34. The serum contained high titers of antibodies to dsDNA, Sm, nRNP, and SS-A/Ro. The simultaneous presence of Werner's syndrome and SLE could be a coincidental occurrence of the two diseases, although it might be due to an abnormality in replication or degeneration of DNA leading to the development of both diseases.