Tactile defensiveness (TD) is a disturbance in sensory processing and is observed in some children with attentiondeficit-hyperactivity disorder (ADHD). TD has been examined in male children with ADHD and in children with ADHD without differentiating by sex. As males and females with ADHD may differ in the clinical expression of the disorder and associated deficits, the aim of this study was to examine sex differences in TD in males and females with ADHD. Non-affected siblings were also examined to investigate familiality of TD. The Touch Inventory for Elementary-School-Aged Children was administered to 47 children with ADHD (35 males, 12 females; mean age 9y 8mo [SD 1y 11mo]), 36 non-affected siblings (21 males, 15 females; mean age 8y 10mo [SD 2y 4mo]), and 35 control children (16 males, 19 females; mean age 9y 5mo [SD 6mo]). Results indicated that females with ADHD displayed higher levels of TD than males with ADHD (who did not differ from control males). This suggests that TD is sex specific and may contribute to the identification of ADHD in females, thus improving diagnostic and therapeutic strength in this underreferred group. Non-affected siblings were unimpaired, regardless of sex, which suggests that TD is specific to the disorder and not part of a familial risk for ADHD.Attention-deficit-hyperactivity disorder (ADHD) 1 is a common neuropsychiatric developmental disorder, which is estimated to affect between 3 and 11% of children and adolescents. 2 The core clinical symptoms of ADHD (inattention, hyperactivity, and impulsivity) are often accompanied by associated symptoms such as sleep problems, reduced motor coordination, and impaired balance. 2 Sex possibly influences the clinical manifestation of ADHD and the extent to which associated symptoms of ADHD occur. Three studies found that females with ADHD showed relatively lower levels of hyperactivity and fewer diagnoses of conduct disorder and other comorbid disruptive behavior problems compared with males with ADHD. 3-5 However, it was also found that females with ADHD have greater intellectual impairment, 4,5 a higher prevalence of the predominantly inattentive subtype of ADHD, 3 and are more at risk for substance-use disorders. 3 One study found no sex difference with respect to impulsivity, academic performance, social functioning, and/or fine motor skills. 4 Further study may help to determine whether differences exist between males and females with ADHD.Relatively little is known about sex differences in disorders associated with ADHD, such as sensory processing disorders. Recent literature suggests that children with ADHD show a disturbance in sensory processing and integration of tactile stimuli. 6-9 One area of dysfunction in sensory processing disorders is called tactile defensiveness (TD). 10,11 TD is often observed in children with autism, learning disability,* fragile X syndrome, emotional disturbances, and specific learning difficulties. [10][11][12][13][14] Individuals with TD show a tendency to 'react negatively and emotionally to certa...