The aim of this study is to examine executive functions in healthy siblings of children with autism spectrum disorder (ASD) and to evaluate the relationship between chronotype and executive functions (EF). This study included 40 healthy siblings (case group) of children with ASD and 40 healthy controls. Executive functions were evaluated by Stroop Test, Serial Digit Learning Test (SDLT) and Cancellation Test (CT). Children’s Chronotype Questionnaire (CCTQ) and Autism Spectrum Screening Questionnaire (ASSQ) were administered to parents. It was determined that the Stroop Test and CT performances of the case group were significantly worse than the control group. There was no difference in SDLT. It was determined that the total CCTQ score of the case group was significantly higher. In addition, a significant positive correlation was found between the chronotype total score and the number of false targets in the second part of CT. In the logistic regression analysis; the chronotype total score, Stroop test fifth part correction number and CT fourth part error number were determined as possible factors in the differentiation of the case and control groups. More studies are needed to evaluate the relationship between executive functions and chronotype in siblings of children with ASD.