OBJECTIVES: To determine the percentage of patients who had a continued diagnosis of attention-deficit hyperactivity disorder (ADHD) from childhood to adulthood in real practice and to examine the association between the sustained diagnosis of ADHD, other mental health comorbidities and the exposure to psychotropic medications. METHODS: A retrospective longitudinal analysis was conducted using the 1995 to 2001 Medicaid claims data. The study cohort were patients 4 - 17 years of age who received a diagnosis of ADHD in the year 1995. These patients were then followed through 2001 to determine the percentage that retained the diagnosis of ADHD. Multivariate regression analysis was employed to assess the association between sustained ADHD diagnosis, other mental health comorbidities (conduct disorder, oppositional defiant disorder, mood disorders, anxiety disorder and substance abuse disorder) and the exposure to psychotropic medications (stimulants, antidepressants, antipsychotics, antianxiolytics, anticonvulsants). RESULTS: A total of 18,131 patients were identified with a diagnosis of ADHD in 1995 and had continuous Medicaid eligibility during the 7 year follow-up period. Out of those only 10,746(57.77%) retained a diagnosis of ADHD in the first year follow-up and merely 1530 (8.43 %) retained the diagnosis of ADHD in 2001. The length of retaining ADHD diagnosis is positively associated with the early exposure to stimulants and  having mental health comorbidities such as mood disorders, anxiety disorder, conduct disorder and oppositional defiant disorder. CONCLUSIONS: The result is in confirmation with previous prospective studies which indicated that ADHD shows a remission with maturation.  However, the proportion of patients retaining ADHD diagnosis in real practice is 60% to 80% lower than the findings of those prospective studies, which suggests a significant gap between knowledge advancement and practice. Further study is needed to clarify the relationship between psychopharmacotherpy and sustained diagnosis of ADHD from childhood to adulthood.