The clearance of bacterial lipopolysaccharide (LPS) from Bacteroides fragilis was studied, using wound chambers implanted subcutaneously in rabbits. The primary skin inflammatory reaction, the Limulus amoebocyte lysate test and the haemagglutination inhibition test all demonstrated a more rapid elimination of LPS from the wound chambers after the second injection, compared to the elimination rate after the first injection given three days earlier. The clearance rate of LPS was significantly higher (0.003 greater than or equal to p greater than or equal to 0.0006) and the number of accumulated leukocytes in the inflammatory exudate significantly lower (p less than or equal to 0.05) after the second injection. Antibodies to B. fragilis LPS in the exudate before the second endotoxin injection was of the 19S IgM class. This suggests that phagocytes in the granulation tissue lining the chamber walls may be of importance in the elimination of endotoxin.