We investigated the absorption routes of endotoxin derived from the intestine of rabbits with or without thoracic duct lymph drainage (TDLD). The intestinal circulatory disorders induced were superior mesenteric artery occlusion (SMAO) and superior mesenteric vein occlusion (SMVO). Detection and quantitation of endotoxin in plasma and lymph were carried out using a synthetic chromogenic substrate (peptide-4-methyl-coumarin amide, MCA). In the SMAO group, endotoxin levels in portal plasma exceeded levels in lymph from the thoracic duct throughout the experiment, and in the SMVO group, the relationship was reversed. In peripheral arterial blood, endotoxin levels were significantly lower in rabbits with TDLD than in those with intact lymphatic system. Intestinal lymphatics probably play an important role in appearance of systemic endotoxemia in non-septic shock.