Extensive studies have reported cognitive abnormalities in neurodevelopmental disorders, such as autism spectrum disorder (ASD). Another line of evidence suggests that stress also affects cognitive functions. In this study, we investigated whether there were associations between stress hormones and cognitive functions in ASD and typically developing (TD) children. Cognitive functions in ASD and TD children were evaluated with a battery of psychological tests for working memory, behavioral flexibility, and social cognition for emotional assessments of others. ASD children exhibited higher hair and salivary cortisol, which reflects chronic and acute stress hormone levels of subjects, respectively, than TD children. Autism-spectrum quotient (AQ) was positively correlated with hair cortisol and the scores of Spence Children's Anxiety Scale in ASD children. In addition, a negative correlation was present between spatial working memory performance and hair cortisol in ASD, but not in TD, children. These results suggest that chronic stress hormone elevation may have relationships with some aspects of cognitive dysfunction in ASD subjects. (C) 2016 The Author(s). Published by Elsevier Ltd on behalf of IBRO.