Abstract: Objective: To study clinical manifestation and image features(CT and MRI) on toxic encephalopathy after inhaling heroin.Methods: Analysed clinic manifestion,image features,treatment and results of three cases.Results: Three patients were the youth,they all had definite histories of inhaling heroin,and they had appearances of clinical manifestations in half month after abrupt abstinence.The disease started in a subacute way.And the main clinical manifestations were progressive dysarthria,unstable walking,reaction retardation,ect.The CT and MRI of brain revealed the change of generalized,symmetrical demyelination in cerebellum hemisphere,basal ganglia,white matter of cerebrum hemisphere,brain stem.By treated with methylprednisolone 3 patients improve remarkably.Conclusions: The diagnozis of heroin toxic encephalopathy should be dependent on the definite history of inhaling heroin and clinical features and imagine features,so we could diagnose and treat the patients of the disease in time.