We describe an unusual case of elderly onset systemic lupus erythematosus (SLE) that presented with disseminated intravascular coagulation (DIC). An 86-year-old man who complained of general malaise was admitted for evaluation and treatment of thrombocytopenia. He was diagnosed as having SLE and DIC based on the criteria of the American College of Rheumatology for SLE (renal involvement, hematological abnormalities, and positivity for antinuclear antibody and lupus anticoagulant) and the criteria for DIC presented by the subcommittee on DIC of the ISTH (a large increase of fibrin degradation products [3 points] and a platelet count <50 x 10(3)/ml [2 points], resulting in a score of 5; a score > or =5 is compatible with DIC). The patient was treated with corticosteroid therapy (30 mg/day); the DIC and SLE remitted, and his renal function improved, but he developed pulmonary tuberculosis. Timely diagnosis, appropriate treatment, and an awareness of the potential for serious infections are of utmost importance when dealing with patients with elderly onset SLE.