AIM: To investigate the effect of high concentration of chlorine gas(Cl 2) exposure on lung haemodynamic and respiratory function in intact and isolated perfused rabbit lungs (IPLs). METHODS: 8 intact and 10 IPLs were exposed to Cl 2 at high concentration(50?10 -4 )for 20 min, as measured group, 8 additional intact and 9 IPLs, which were similarly treated but not exposed to Cl 2, served as controls. The changes of lung weigh of IPL(△W)?pressure of pulmonary artery(Pa)and venous pressure(Pv)?airway pressure and tidal volume(TV) were continuously measured and recorded simultaneously. RESULTS: In IPL group: While the perfusing blood flow was kept constant (133.3 mL/min), and Pv did not change, following the exposure, the Pa increased slightly, then the lung weight were increased significantly and the TV decreased . Hematocrit of perfusate of EIPL and parameters of lung water increased also. In intact group : Pa increased slightly, respiratory rate accelerated immediately, and TV decreased. CONCLUSION:Although mean Pa increased continuously and slightly in both intact and IPL group following the exposure to high concentration of Cl 2, the primary cause of edema was most likely to alter pulmonary capillary permeability. The respiratory rate accelerated and TV decreased due to exposure to Cl 2 enhanced hypoxia of intact rabbits.