The clinical significance of antinative DNA antibodies as measured by the Farr test was investigated in 10 patients with the articular features of rheumatoid arthritis. 5 of these patients also satisfied criteria for a diagnosis of systemic lupus erythematosus (SLE) and might be classified as rheumatoid/lupus overlap syndromes or as rheumatoids with systemic complications. None had evidence of renal disease and 3 of the 5 had Sjgøren's syndrome. The sixth patient had aggressive peripheral arthritis, alopecia, and Sjøgren's syndrome and developed anti-DNA antibodies after treatment with penicillamine. All of the 4 rheumatoid patients with no clinical features typical of SLE had some special disease feature. The first had subclinical liver disease and the other 3 had Sjøgren's syndrome in addition to localized vasculitic skin ulceration (2) and pulmonary fibrosis (1).