This brief report examines the implementation of dietary intervention utilizing the specific carbohydrate diet (SCD) for the management of gastrointestinal issues in a 4 year old boy diagnosed with Autism Spectrum Disorder (ASD) and Fragile X Syndrome (FXS). Data relating to anthropometrics, dietary intake, blood markers, gastrointestinal (GI) symptoms, sleep issues, and behavioral concerns were gathered at baseline and after 4 months of dietary intervention. The dietary intervention was well tolerated. Improvements in nutrient status, GI symptoms, and behavioral domains were reported. The use of the SCD protocol in children with ASD/FXS and GI symptoms warrants further investigation.