Background Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition that often results in poor academic performance. Little is known about how ADHD manifests in residents and fellows. Objective To describe the prevalence and phenotype of ADHD among residents and fellows referred to a centralized remediation program. Methods We conducted a retrospective review of data obtained from referrals to a single-center centralized graduate medical education remediation program from 2017 to 2023. Data included demographic variables, ADHD and mental health history, and training performance characteristics. ADHD was determined by self-report, clinical diagnosis by mental health provider, or neuropsychological testing. Results A total of 173 trainees were referred in the study period. The prevalence of ADHD was 20% (35 of 173). ADHD was most commonly diagnosed in childhood (57%, 20 of 35); however, 26% (9 of 35) were diagnosed during or after medical school. Only 37% (13 of 35) were on medication, and 69% (24 of 35) disclosed at least one concomitant mental health diagnosis. Performance deficits were common in professionalism (69%, 24 of 35), organization/efficiency (O/E; 63%, 22 of 35), and medical knowledge (46%, 16 of 35). Repeated errors in patient care were made by 34% (12 of 35); 29% (10 of 35) failed at least one board examination, and 20% (7 of 35) required extension of residency or fellowship training. When compared to referrals without ADHD, residents and fellows with ADHD were more likely to struggle with O/E, failure to engage, and repeated errors. Conclusions One in 5 trainees referred to a GME remediation program had ADHD, and most were not being treated for ADHD when referred. The deficits identified suggest an ADHD phenotype in GME which may be considered for struggling residents and fellows.