This study aimed to evaluate the effect of linguistic complexity and individual background variables (i.e. linguistic and cognitive abilities, degree of autistic traits, and sex) on speech disfluencies in autistic young adults and controls. Thirty-two 19- to 33-year-old autistic adults and 35 controls participated in this study. The frequency of disfluencies and stuttering severity were evaluated based on a narrative speech task. Linguistic complexity was assessed by evaluating the syntactic structures of the narratives. Cognitive and linguistic abilities were assessed using the General Ability Index (GAI), Verbal Comprehension Index (VCI) and Perceptual Reasoning Index (PRI) from the Wechsler Adult Intelligence Scale IV. Autistic traits were measured using the Autism Spectrum Quotient (AQ). Multiple-linear regression analyses (syntactic complexity, GAI, AQ, sex, and group status as predictors) showed that (a) syntactic complexity predicted total and stuttering-like disfluencies and stuttering severity, (b) GAI predicted typical disfluencies, and (c) sex predicted total, typical, and stuttering-like disfluencies. Additional correlation analyses revealed negative association between PRI and disfluencies in the control group but not in the autistic group. No connection was found between AQ and disfluencies. It seems that while some connections between disfluencies and individual cognitive features were found, some of the possible contributing factors for greater speech disfluency might differ between autistic and typical speakers.