In this clinical case report we describe the effects associated with the administration of a supplement constituted by chondroitin sulfate, vitamin D 3 and oleic acid (Rerum ®) on the symptoms of Autism Spectrum Disorders (ASD). 44 patients (11 females and 33 males) were administered this supplement for a period of two months and variations of symptomatology were evaluated by the Clinical Global Impression of Improvement (CGI-I). 32 out of 44 subjects (73%), showed improvements in the two months of observation. In the group of female subjects, 9 out of 11 (81%) showed improvements and, among these, 6 out of 9 (66%) showed moderate to very considerable improvements. In the group of male subjects, 24 out of 33 (73%) showed improvements and, among these, 22 out of 24 (91%) showed moderate to very considerable improvements. We attribute these remarkable results to the effects of the supplement on the endocannabinoid system as it relates to neuro-inflammation and neuro-immune alterations.