The frequency of micronuclei in peripheral blood lymphocytes of ASD patients were monitored with the CBMN Assay. We have evaluated a random population of 46 children and 5 adults aged 2-24 years with appropriate age and sex matched controls. The patients were first clinically pre-screened with help of physician. Peripheral blood samples were collected from antecubital vein, cultured using RPMI-1640medium and treated with Cytochalasin-B. Harvested cells were stained using giemsa and a total of 1000 BN cells were scored for all the subjects. All the patients were analyzed cytogenetically and categorized clinically using the DSM-IV manual. Patients with PDD, ADHD, MR, AS and both PDD/ADHD, showed significant proportion of DNA damage which was statistically significant when compared with age and sex matched controls. This study shows a significant level of DNA damage in ASD patients when compared to controls. To an extent, environmental, occupational exposures, lifestyle factors, dietary deficiencies and different diseases have also added up to the rise. Important knowledge gap still remains about the characteristics of micronuclei and other nuclear abnormalities, including the basic biology explaining the appearance of various cell types in autism patients which may be addressed by further studies.