Objective: Sluggish cognitive tempo (SCT) and autistic-like traits (ALTs) may occur together in attention-deficit/hyperactivity disorder (ADHD). This study aimed to explore a possible association between SCT and ALTs in a sample diagnosed with ADHD. Method: A total of 147 children and adolescents with ADHD aged 6 to 14 were included in the study. The parents completed Barkley's Child Attention Survey and Autism Spectrum Screening Questionnaire. A mental status examination and a semistructured interview were applied to detect comorbidities. Results: Approximately 54,2% (n = 26) of the participants with high ALT levels had higher SCT. SCT symptoms were positively associated with ALT levels. Moreover, the association between SCT and ALTs remained significant after controlling for age, gender, parental ages at giving birth and inattentive presentation of ADHD. SCT predicted higher levels of ALTs, and ALTs predicted higher levels of SCT. Conclusion: The present study provided evidence of an association between SCT and ALTs in ADHD children even when controlled for inattentive presentation and other child- and parent-related variables. The findings may contribute to clarifying some pieces of the clinical picture by revealing the interrelationship between SCT and ALT accompanying ADHD in understanding the underlying transdiagnostic structures of clinically heterogeneous ADHD. [This study was presented as an oral presentation at 28th Turkish National Child and Adolescent Psychiatry Congress, 9-12 May 2018, Istanbul--Turkey.]