Children with Autism (ASD) often suffer from motor abnormalities and the main inhibitory neurotransmitter GABA has been linked to ASD. We measure GABA in the primary sensorimotor cortex using MRS and measure praxis (social gesturing) in children with ASD and healthy children (TDC). We show that GABA is differentially related to social gestures in children with and without ASD. This suggests a complex relation between inhibition and gesture function. Reduced GABA levels may impair the performance of gestures with a communicative purpose, contributing to autistic phenotypes. Understanding the GABA system in ASD is important for developing patient-specific treatment in ASD.