Objective: To examine the discriminatory validity of the Wender Utah Rating Scale (WURS) and its five suggested subscales (Conduct Problems, Impulsivity Problems, Mood Difficulties, Inattention/Anxiety, Academic Concerns) in a Finnish sample. Method: WURS was administered to 114 adults, aged 18 to 55 years. Participants with ADHD (n = 37) and dyslexia (n = 36) were compared with healthy controls (n = 41). Results: The ADHD group scored significantly higher than the control group on all subscales. Compared with the dyslexia group, the ADHD group did not differ in Mood Difficulties or Academic Concerns. Using the total score, the positive predictive value was 0.53 in this sample and only 0.21 when the prevalence of ADHD was taken into account. Conclusion: Three out of five domains of WURS are reliable indicators of ADHD. Domains with low discriminatory power, low general prevalence of ADHD, and other developmental disorders within the population decrease the accuracy. (Contains 1 note, 5 tables and 1 figure.)