Sensory Modulation Dysfunction (SMD) is characterized by an inability to consistently and accurately grade responses to sensory information. SMD, and specifically sensory over-responsivity (SOR), has been correlated with stress and anxiety in some developmentally delayed populations and has been associated with structures and functions of the hypothalamic-pituitary adrenal (HPA) axis. Recent attention has been given to HPA functioning in children with Attention Deficit Hyperactivity Disorder (ADHD), with a majority of studies identifying blunted or diminished cortisol patterns. In contrast, elevated cortisol has been associated with anxiety and anxious behaviors in both animal and human studies. The purpose of this study was to determine if SOR may be a contributing factor in determining stress reactivity patterns in children with ADHD or related to elevated levels of anxiety in this population.Twenty four children between the ages of six and ten with ADHD and 24 children without ADHD were recruited for this study. Parents completed a Revised Children's Manifest Anxiety Scale (RCMAS) with their child. Children in the ADHD group were divided into SOR (ADHDs) and non-SOR (ADHDt) groups using the Sensory Over-Responsivity Inventory (SensOR). All children participated in a Sensory Challenge Protocol. Two pre-challenge and seven post-challenge measures of salivary cortisol were taken. The relationship between SOR and anxiety was examined using an Analysis of Variance (ANOVA) and a Fishers exact test to look for differences among group medians and compare scores to clinical cut-off standard. Cortisol patterns were examined using a mixed-effects ANOVA to determine if stress reactivity was significantly different between groups.No baseline differences in salivary cortisol were found between groups. In response to a sensory challenge, there was a borderline significant difference found between the ADHDt and ADHDs group (p=0.056) and a significant difference between ADHDt and the typical (p=0.014) group; with cortisol levels being significantly lower in the ADHDt group. Scores for total anxiety indicated that the ADHDs group was significantly more anxious than both the ADHDt and control group. These results indicate that SOR may alter the stress response in children with ADHD and contribute to increased anxiety in this population.