Autistic disorders comprise a very large segment of behavioral disturbances. Symptom-wise they range from its severest form, the early infantile severe autism, to late onset/adolescent type mild autism of Asperger syndrome. In between there exist other behavioral disturbances such as pervasive developmental disorder and attention deficit-hyper-activity disorder. Since there is no known cure, and both diagnosis and intervention are fraught with great challenges, a very large number of investigations have been conducted for the last 20 years. Early ones were done through genetic marker-based linkage studies in multiplex families. They were followed by observations in a large number of syndromes associated with autism. The ever increasing incidence withdrew attention to environmental and epigenetic factors. Although the first two approaches revealed valuable information, the results of the latter studies remained inconclusive. Finally a very recent breakthrough clarified some of the research questions and indicated germline mutations in some cases. At present the knowledge in this field indicates to an unusual medical problem: “Each autistic case is a unique patient with his/her own unique genetic defect”. This poses the most difficult challenge to the physician as well as to the geneticist who must do very detailed genetic studies nearly in every single case and try to make a meaningful conclusion and then start looking for possible pharmacologic intervention. In this review we will briefly discuss the diagnostic criteria and methods used for diagnosis followed by a detailed discussion of genetic basis of the disease and concluding with intervention procedures in current use.