Autism is a severe neurodevelopmental disorder with a strong genetic basis.The methyl-CpG binding protein 2 gene (MECP2) is a dosage-sensitive gene in brain development and has been implicated as a candidate gene for autism. Duplication of the MECP2 gene has been reported in a few boys with autistic features. To further investigate the association of MECP2 duplication with autism, the authors performed real-time quantitative polymerase chain reaction (PCR) to detect copy number variations of the MECP2 gene in 82 autistic boys. No copy number variation was found in these patients, indicating that duplication of the MECP2 gene is not frequent in autistic patients. The authors consider that duplication of the MECP2 gene has no major effect on the susceptibility to autism. Replication of studies in a large-sized sample and a well-characterized subgroup of autism are warranted to further identify the association of MECP2 gene duplication with autism.