Autism spectrum disorder (ASD) is a neurodevelopmental condition affecting the daily lives of people who suffer from it. Children with ASD exhibit severe behavioral, cognitive, and electrophysiological symptoms, including hyperactivity, intellectual disability, and cortical hyperexcitability. Recent studies have reported that the gut microbiota may be responsible for some symptoms associated with ASD. Supplementation with probiotics could thus normalize the intestinal microbiota. As part of this open clinical study, probiotic treatment was administered to 15 children with ASD. The main aim of this study is to explore the electrophysiological changes following a 14-week Bio-K+ treatment in these children.