Thirty-six patients were studied for the presence of the lupus anticoagulant and its possible clinical and laboratory associations. Seven patients were found to have the anticoagulant. These patients had a significantly increased incidence of both thromboembolic complications (5/7 vs. 2/29) and thrombocytopenia (4/7 vs 4/29). None of them had a bleeding tendency. Except for these associations, patients with the anticoagulant did not differ from those without the anticoagulant by any demographic, clinical, or laboratory parameter. The present study confirms observations that SLE patients with the lupus anticoagulant have an increased risk of thrombosis.