Objective: The therapeutic approach of traditional chinese Medicine (TCM) in autism spectrum disorder (ASD) is a functional one. To study the efficacy, safety and functional brain change from the use of tongue acupuncture (TAC) on ASD children. Methods: 21 autistic boys (3e16 years old) were randomly assigned to TAC group (TAC: n Z 12; receiving daily TAC for 8 weeks) or control (C: n Z 9; no acupuncture). Primary outcome measures included Autism Treatment Evaluation Checklist (ATEC), Reynell Language Developmental Scale, Symbolic Play Test (SPT), Functional Independence Measure for Children (WeeFIM), Clinical Global Impression (CGI) Scale and Cerebral FDG Metabolism by PET. Results: There were significant improvement in speech domain of ATEC (p Z 0.030), Self-care domain of WeeFIM (p Z 0.021), cognition domain of WeeFIM (p Z 0.001) and Total score domain of WeeFIM (p Z 0.001) in TAC group compared to the C group. There were significant difference in positive clinical response between C and TAC group in language (p Z 0.0211), functional (p Z 0.0011), parental Impression criteria (p Z 0.0003) and overall cerebral glucose metabolism (p Z 0.0451) using ROC criteria. No significant association of PET Glucose Metabolism with Clinical response was found. None of the children developed any side-effects.