The presence of a lupus anticoagulant was evaluated in patients with Bechet's disease by the kaolin clotting time method. Four percents (three patients) of 69 patients analyzed were found positive for the lupus anticoagulant. However, no statistically significant association existed between the presence of this antibody and the presence of thrombosis, clinical activity, clinical type, antinuclear antibodies and the positive VDRL test.