Some clinical studies on attention deficit hyperactivity disorder (ADHD) have been found to overlap those of studies on personality, particularly those on the Novelty Seeking trait (NS) as measured by the Junior Temperament and Character Inventory (JTCI). The aim of this study was to evaluate the potential role of NS in clinical research on ADHD. We enroled 146 ADHD children (125 boys; mean age = 9.61, S.D. = 2.50) and 223 age- and gender-matched control children (178 boys; mean age = 9.41, S.D. = 2.30). All the parents filled in the JTCI for the evaluation of personality according to Cloninger’s model. An exploratory factor analysis differentiated the NS items that concern ‘Impulsivity’ (NS1) from those that concern other features (NS2). Multivariate Analysis of Variance (MANOVAs) revealed significant differences between ADHD children and non-ADHD children in temperamental dimensions: the scores of ADHD children were higher than those of non-ADHD children in Total NS, NS1-Impulsivity and NS2. Our results show that the NS dimension of the JTCI in ADHD children is higher than in non-ADHD children, even when a correction is made for impulsivity items. This finding suggests that the NS trait plays a central role in ADHD diagnosis even when items referred to impulsivity are removed from the NS scale.