This study investigated the role of endotoxaemia in the development of hyperdynamic circulation observed in rats with extrahepatic (high collateralization) or intrahepatic (low collateralization) portal hypertension. Compared with sham‐operated rats, decreased mean arterial pressure and systemic vascular resistance were detected on days 1, 4 and 14 following partial portal vein ligation. By day 1, the cardiac index of portal vein‐ligated rats was similar to that of sham‐operated rats and progressively increased, thereafter, reaching statistically higher values on days 4 and 14. No differences in plasma endotoxin levels were found between portal vein‐ligated and sham‐operated rats throughout the observation period. Both carbon tetrachloride‐induced cirrhotic rats with and without ascites had a higher cardiac index and lower systemic vascular resistance than those of control rats, and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma endotoxin levels were higher in cirrhotic rats with ascites (8.6±2.0 pg/mL; P < 0.01) than those of control rats (2.2±0.3 pg/mL) and cirrhotic rats without ascites (2.4±0.6 pg/mL). These results suggest that factors other than endotoxaemia play a role in the development of hyperdynamic circulation observed in rats with extrahepatic portal hypertension and cirrhotic rats without ascites, but that endotoxaemia may contribute to the maintenance of hyperdynamic circulation found in cirrhotic rats with ascites. The severity of liver disease may be a more important factor than the presence of portosystemic shunting for the development of endotoxaemia in portal hypertensive states.