Autism Spectrum Disorder is a neurodevelopmental disorder. Recent data suggest that probiotics can reduce some symptoms of this disorder and Lactobacillus plantarum PS128 has been reported to be especially useful. We recruited a sample of 131 autistic children and adolescents (M:F = 122:19; age: 86.1 ± 41.1 months) and evaluated their changes after use of probiotics by mean of CGI. We found some significant improvements with very few side effects; these positive effects were more evident in younger children. Patients taking Lactobacillus plantarum PS128 had greater improvements and fewer side effects than those taking other probiotics. Our real-life data are consistent with existing literature showing a specific effect of Lactobacillus plantarum PS128 in Autism Spectrum Disorder.