Attention Deficit Hyperactivity Disorder (ADHD) is the most common neurodevelopment disorder diagnosed during childhood, and often lasts throughout adulthood, affecting approximately 8% of the population eligible for military service in the US. According to the DoD Instruction 6130.03 Volume 1, ADHD is disqualifying from military service if with: (1) a recommended or prescribed Individualized Education Program, 504 Plan, or work accommodations after the 14th birthday; (2) a history of comorbid mental disorders; (3) prescribed medication in the previous 24 months; or (4) documentation of adverse academic, occupational, or work performance. Recruits disqualified for ADHD may access upon receipt of an approved accession medical waiver. Recent recruiting challenges have created a need to better understand the prevalence of disqualifying ADHD among recent recruits and assess the impact of pre-existing ADHD on readiness, including a service member’s ability to complete their first enlistment term. Leveraging longitudinal data on service members in all DoD Military Departments from pre-enlistment application to end of service, this study aimed to describe the prevalence and trends of disqualifying ADHD among recent recruits, compare timing to early separation (within first three years of service) between ADHD-disqualified recruits and medically qualified recruits, and assess risk for early separation, including adverse attrition, disability discharge, and discharge due to conditions that existed prior to service (EPTS). Considering the growing prevalence of ADHD among U.S. adolescents, the outcomes of this study may aid policymakers in refining medical standards and behavioral health policies. Of the approximately 1.3 million recruits medically screened at MEPS from FY 2016-2020, nearly 8,300 (0.6%) were medically disqualified for ADHD, ranking ADHD as the ninth most common medical disqualification. The yearly trend for ADHD disqualifications remained relatively stable at about 5 to 7 per 1,000 recruits. Roughly half of ADHD-disqualified recruits accessed, with accession rates ranging from 41% (Army) to 53% (Air Force). While 1 in 7 ADHD-disqualified and waived recruits adversely discharged within the first three years of service, they had higher retainability with lower risk of any early adverse discharge when compared to medically qualified recruits, demonstrating the effectiveness of the DoD disqualification and waiver policies. This study is currently ongoing and results evaluating ADHD-related medication use and medical reasons for discharge, including DoD disability and EPTS, are pending. Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the author, and are not to be construed as official, or as reflecting true views of the Department of the Army or the Department of Defense.