Given the heterogeneity of Attention-Deficit Hyperactivity Disorder (ADHD), there is a constant need for proper diagnosis, employing more accurate, efficient, patient-friendly, and clinician-friendly tools. We developed a Greek version of the National Institute for Children's Health Quality (NICHQ) Vanderbilt ADHD Diagnostic Parent Rating Scale (VADPRS) for follow-up assessment and examined its reliability and validity. A total of 100 schoolchildren (65 girls and 35 boys) between 7 and 12 years old with ADHD were included in the study. The internal consistency and test-retest reliability were examined via principal component analysis. Three-component structure in our study accounts for 74.63% of the tool's variance. The questions' loadings onto the factors and the internal reliability of the three factors were satisfactory. Finally, the reliability of all factors presented was found adequately high, confirming the high internal consistency of the items. Our results suggest that the Greek version of the VADPRS-follow-up may be used as an accurate psychometric instrument for the purposes of diagnosing ADHD. Furthermore, the combined use of the VADPRS-follow-up with other widely accepted tools, such as the ADHD Rating Scale-IV, may present clinical utility in collating parent information concerning the behavioural phenotype of their children.