Background: Emotion dysregulation is increasingly recognized as highly prevalent and impairing in autistic individuals. Yet, a large majority of studies have considered emotion dysregulation in youth only, and most of them did not consider sex differences in emotion dysregulation manifestation. Objectives: In the present study, we aim to investigate sex differences relative to emotion dysregulation in autistic adults without intellectual disability as well as its relationship with different factors potentially involved in emotion dysregulation (e.g. camouflaging, alexithymia, suicidality, quality of life). Self-reported emotion dysregulation will be assessed in autistic adults but also in females with borderline personality disorder, given that emotion dysregulation is particularly enhanced in this population. Design: Cross-sectional, prospective, controlled. Methods: Twenty-eight autistic females, 22 autistic males and 24 females with borderline personality disorder were recruited from a dialectical behavior therapy program waiting list. They completed several self-report questionnaires measuring emotion dysregulation, alexithymia, suicidality, quality of life, camouflaging borderline symptoms and autism severity. Results: Most emotion dysregulation subscale scores and alexithymia scores were heightened in autistic females compared to females with borderline personality disorder and, to a lesser extent, compared to autistic males. Independently of borderline personality disorder symptoms, emotion dysregulation was related to alexithymia and poorer psychological health in autistic females, whereas it was mostly related to autism severity, poorer physical health and living conditions in autistic males. Conclusion: Our results suggest that emotion dysregulation is a major difficulty of autistic adults without intellectual disability eligible for dialectical behavior therapy, and this is especially the case for autistic females. There seem to be different sex-specific factors involved in emotion dysregulation found in autistic adults, which highlight the need to target-specific domains (e.g. alexithymia) in the treatment of emotion dysregulation in autistic females. ClinicalTrials.gov Identifier: NCT04737707 https://clinicaltrials.gov/ct2/show/NCT04737707