Children diagnosed with autism who received a fecal microbiota transplant (FMT) had nearly 50% less severe autism symptoms up to two years later. Eight weeks after receiving a FMT, the severity of autism spectrum disorder (ASD) symptoms was 23% lower than at baseline, as assessed by the Childhood Autism Rating Scale (CARS). Two years after the FMT, their ASD symptom severity was 47% lower than baseline. The improvements in the CARS were positively correlated with percent changes in Gastrointestinal Symptom Rating Scale (GSRS) scores, implying that gastrointestinal relief provided by the FMT may also ameliorate behavioral severity in children with . . .