Autism is a neurodevelopmental disorder, and genetic factors play an important role in its pathogenesis. Earlier findings suggest the CNTNAP2 as a predisposition locus of autism, but no study has been carried out on the possible association of CNTNAP2 with autism in the Chinese Han population.In this study, three single nucleotide polymorphisms located within the CNTNAP2 were genotyped in 185 Chinese Han autistic families by polymerase chain reaction-restriction fragment length polymorphism analysis, followed by a transmission disequilibrium test.The results show that a common noncoding variant (rs10500171) is associated with the increased risk for autism, and haplotype T-A (rs7794745- rs10500171, P=0.011) and haplotype A-T-A (rs10244837- rs7794745- rs10500171, P=0.032) also showed evidence of association.The results of family-based association study suggested that the CNTNAP2 is a susceptibility gene of autism in the Chinese Han population.