Objectives: Autism spectrum disorder (ASD) is a major neurodevelopmental disorder characterized by persistent deficits in social communication along with restricted, repetitive patterns of behaviour and interests. FMR1 gene, which causes Fragile X syndrome (FXS), is the most common single-gene contributor to ASD. Variations in CGG repeat length within the 5' untranslated region of FMR1 are central to the etiology of FXS. Given the established connection between FXS and ASD, this study investigated whether the trinucleotide repeat region of FMR1 is associated with ASD in Bangladeshi children. Methods: Seventy-one children participated in the study, including 39 with ASD and 32 age-matched controls. The FMR1 region was amplified using polymerase chain reaction and subsequently sequenced. Results: There was no statistically significant difference in the number of CGG repeats between patients with ASD and controls (p>0.01), with the most common repeat number being 27 in both groups. Interspersion of the two AGG trinucleotides among the CGG repeats was the most common pattern found in the study participants, with frequencies of 56.67% and 50.00% in the ASD and the control groups, respectively. Conclusion This study provides preliminary evidence that CGG repeat expansion in the FMR1 gene is unlikely to represent a major genetic contributor to ASD in Bangladeshi children. However, given the limited sample size, further investigations with a larger cohort are required to confirm these findings.