The role of the genetic polymorphism within the promoter region of the serotonin transporter (5-HTT) gene is under discussion as a modulator for personality traits and a risk factor for several mental disorders including attention deficit hyperactivity disorder (ADHD). Here we report a significant association of this polymorphism with scores on the Wender Utah Rating Scale, which was used for the assessment of a history of ADHD-associated symptoms, indicating a higher frequency of the long variant allele in individuals with high scores. We found no association between the 5-HTT polymorphism and personality traits according to the Eysenck Impulsivity Questionnaire and the Freiburg Personality Inventory, respectively, except a significant association with social orientation. Thus, our study supports the recently reported finding of an association of the 5-HTT polymorphism with ADHD. However, since a dimensional assessment of ADHD-related symptomatology was used in our study instead of a diagnostic approach, we are now on the way in performing further studies regarding diagnostic discrimination and comorbidity.