Endotoxins are large heat stable lipopolysaccharides, which are found in the cell wall of gram negative bacteria. It has been assumed that the intestinal bacteria are the primary source of the plasma endotoxin in cardiac surgery patients.Lactobacilli have been reported as effective in counteracting gram negative bacteria in the gut.Thus Lactobacilli may be effective in reducing the endotoxin rise associated with cardiopulmonary bypass, which may potentially reduce the incidence of the syndrome of generalised inflammation and low systemic vascular resistance post cardiopulmonary bypass.