The study is to analyze the clinical and cytogenetic investigation on patients with Attention Deficit/ Hyperactivity Disorder (ADHD) from South Indian population. Cytogenetic analysis of 30 patients carried out by using human leukocyte culturing method and clinical analysis were carried out for all the cases with the help of physicians. A significantly higher number of chromosomal aberrations were observed in all patients when compared with the controls (p < 0.001). The detection of chromosomal anomalies as a probable cause of ADHD is very significant in genetic consultations genetic counseling, awareness and management of attention deficit children.