Objective To examine the differences on diagnosing attention deficit and hyperactivity disorder (ADHD) between Diagnostic and Statistical Manual of Mental Disorder (DSM-IV) and Chinese Classification of Mental Disorders,Third Edition (CCMD-3). Methods 172 highly suspected ADHD patients diagnosed by senior psychiatrists and referred to psychiatric clinic were enrolled in the study,and their parents were requested to fill in two scales based on DSM-IV and CCMD-3 criteria.All these children were divided into three subtypes according to the diagnostic criteria,including Predominantly Inattentive Type(PI),Hyperactive/Impulsive Type(HI),and Combined Type(CT).Results 162 patients were conformed by the DSM-IV standard (PI=53,HI=6,CT =103),while all the patients met the CCMD-3 standard (PI=39,CT=133).The rate of CT subtype based on CCMD-3 was higher than that of DSM-IV criterion(77.3% vs 66%,P=0.023).The test based on 156 cases which both matched DSM-IV and CCMD-3 CT or PI subtypes standards showed that two scales had moderate goodness of fit on recognizing subtypes of ADHD(Kappa=0.587).Furthermore,McNemar Test also proved that the rates of subtypes of ADHD in DSM-IV were different from those of CCMD-3(P=0.00).The positive rates of items in CCMD-3 standards were higher than those of DSM-IV,and items related to learning problems had higher positive detection rates in both standards. 【Conclusions】 DSM-IV is more rigorous than CCMD-3 on diagnosing ADHD,and higher percentage of patients is clustered as CT type in CCMD-3 criterion.Attention deficit symptoms are more common than hyperactivity and impulsive symptoms in ADHD children.