Abstract: Objective To establish a rabbitmodel of delayed encephalopathy after inhaltion CO poisoning.Methods Thirty two rabbits were exposed to carbonmonoxide for 20 min at the flux of 0.2 L/min and then closed tightly in a cabinet for 6 h.Carbonyl hemoglobin of vein blood was measured.MRI function technique was applied to observe dynamicly the cerebral damage at 1h,3d,5d,and 7d after the poisoning.The appearant diffusion coefficient(ADC)value of rabbits' cerebral cortex was measured and compared.Results The peripheral blood value of carbonyl hemoglobin raised in 0.5 h after the poisoning,and reached the highest after 4h.All the ADC value of cerebral cortex of poisoned rabbits descended after 1h compared with the ADC value before the exposure.There was nostatistical significance at the different tmie after the exposure(P>0.05).In delayed encepha lopathy group,the cerebral cortex ADC value of exposed rabbits showed a statistical significance(P<0.05)compared with the value before the exposure.The pathological findings were coincided with the imaging apearances.Conclusion The ADC value is very important in evaluating the acute CO poisoning,and it can predict in itially the occurrence of delayed encephalopathy induced by carbon monoxide poisoning.