Previous studies suggest that systemic endotoxemia in peritonitis is mainly related to lymphatic transport via the thoracic duct. Rats with fecal peritonitis but with or without a lymph draining thoracic duct fistula were studied with reference to the concentrations of endogenously produced endotoxin in arterial plasma, hemodynamic parameters, organ blood flow, blood corpuscle parameters, glucose and lactate metabolism and survival. Lymph drainage significantly reduced the endotoxin concentrations in arterial plasma, but did not totally prevent systemic endotoxemia, and was related to maintained total peripheral vascular resistance. On the other hand, peritonitic rats without lymph drainage, and consequently higher endotoxin concentrations, had a significant fall in vascular resistance combined with a compensatory rise in cardiac output. Lymph drainage also contributed to a smaller decrease of platelet and leucocyte counts while no effect was observed on glucose metabolism. Despite the effect of lymph drainage on hemodynamic and hematologic responses no effect on survival time was recorded.