Infections with Bacteroides species have been noted to occur in association with cases of thrombophlebitis. This association has led to the speculation that the microorganisms themselves may contribute to the pathogenesis of thrombus formation through elaborated enzymes, including heparinases, or by interactions between the clotting cascade and the unique structure of the Bacteroides lipopolysaccharide. Anti-phospholipid antibodies have been linked with hypercoagulable states and thrombus formation. Although a number of infections have been associated with the transient production of anti-cardiolipin antibodies, the effect the antibodies may have in contributing to thrombus formation is not well understood. The occurrence of Bacteroides species infection with transient anti-cardiolipin antibody has not been previously reported.