Background Autistic adults, particularly women, are more likely to experience chronic ill health than the general population. Central sensitivity syndromes (CSS) are a group of related conditions that are thought to include an underlying sensitisation of the central nervous system; heightened sensory sensitivity is a common feature. Anecdotal evidence suggests autistic adults may be more prone to developing a CSS. This study aimed to investigate the occurrence of CSS diagnoses and symptoms in autistic adults, and to explore whether CSS symptoms were related to autistic traits, mental health, sensory sensitivity, or sex. MethodsParticipants included 982 autistic adults (male = 409, female = 563, other = 9, mean age = 44.5) registered at the Netherlands Autism Register, who completed questionnaires assessing autistic traits, sensory sensitivity, CSS, physical and mental health symptoms. The reliability and validity of the Central Sensitization Inventory (CSI) in an autistic sample was established using exploratory and confirmatory factor analyses. Chi2 analyses, independent t-tests, ANOVA, hierarchical regression analysis and path analysis were used to analyse relationships between CSS symptoms, autistic traits, measures of mental health and wellbeing, sensory sensitivity, age and assigned sex. Results21% of participants reported one or more CSS diagnoses, and 60% scored at or above the clinical cut-off for a CSS. Nonbinary and female autistics were more likely to report a CSS diagnosis and experienced more CSS symptoms than males. Sensory sensitivity, anxiety, age and sex were significant predictors of CSS symptoms, with sensory sensitivity and anxiety fully mediating the relationship between autistic traits and CSS symptoms. Limitations Although this study included a large sample of autistic adults, we did not have a control group or a CSS only group. ConclusionsCSS diagnoses and symptoms appear to be very common in the autistic population. Increased awareness of an association between autism and CSS should inform clinicians and guide diagnostic practice, particularly for females where CSS is common and autism under recognised.