Autism Spectrum Disorder (ASD) is a brain-based, developmental condition. Children with ASD have communication difficulties, narrow interests, and repetitive behaviour. ASD is defined by a certain set of behaviors and is a “spectrum condition” that affects individuals differently and to varying degrees. The role of copy number variations with specific gene regulation and human diseases is already well documented. Chromosomal microarray analysis should be considered as a first-tier genetic diagnostic test for autism spectrum disorders because of its strong ability to detect chromosomal abnormalities. The Chromosomal Microarray Analysis (CMA) plays an important role to rule out the CNVs that can cause the Autism. The reported yield of an array is approx. 10-15%. Whereas the diagnostic yield of G banded karyotyping is only 3%.The diagnostic yield is found to be significantly higher when more complex abnormalities such as ID, Dysmorphism are also present along with ASD. In this study, it was explained about CMA for 100 postnatal cases of autism, as a first-tier test followed by G banded karyotyping.