BACKGROUND:The goal of this study was to validate the pilot Adult ADHD Self-Report Scale (pilot ASRS) versus standard clinician ratings on the ADHD Rating Scale (ADHD RS). METHOD:Sixty adult ADHD patients took the self-administered ADHD RS and then raters administered the standard ADHD RS. Internal consistency of symptom scores was assessed by Cronbach's alpha. Agreement of raters was established by intra-class correlation coefficients (ICCs) between scales. RESULTS:Internal consistency was high for both patient and rater-administered versions (Cronbach's alpha 0.88, 0.89, respectively). The ICC between scales for total scores was also high (0.84); ICCs for subset symptom scores were also high (both 0.83). There was acceptable agreement for individual items (% agreement: 43%-72%) and significant kappa coefficients for all items (p < 0.001). CONCLUSIONS:The pilot Adult ADHD Self-Report Scale symptom checklist is a reliable and valid scale for evaluating ADHD for adults and shows a high internal consistency and high concurrent validity with the rater-administered ADHD RS.